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7c60335e24a3d5994ae26c1f1c216e8ee2bf6ddd
openGauss-server/src/gausskernel/runtime/executor/nodeHash.cpp
wanghao19920907 7c60335e24 添加安全函数返回值检查
2023-02-06 19:14:29 -08:00

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/* -------------------------------------------------------------------------
*
* nodeHash.cpp
* Routines to hash relations for hashjoin
*
* Portions Copyright (c) 2020 Huawei Technologies Co.,Ltd.
* Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/gausskernel/runtime/executor/nodeHash.cpp
*
* -------------------------------------------------------------------------
*
* INTERFACE ROUTINES
* MultiExecHash - generate an in-memory hash table of the relation
* ExecInitHash - initialize node and subnodes
* ExecEndHash - shutdown node and subnodes
*/
#include "postgres.h"
#include "knl/knl_variable.h"
#include <math.h>
#include <limits.h>
#include "access/hash.h"
#include "catalog/pg_partition_fn.h"
#include "catalog/pg_statistic.h"
#include "commands/tablespace.h"
#include "executor/exec/execdebug.h"
#include "executor/hashjoin.h"
#include "executor/node/nodeHash.h"
#include "executor/node/nodeHashjoin.h"
#include "miscadmin.h"
#include "optimizer/clauses.h"
#include "optimizer/streamplan.h"
#include "pgstat.h"
#include "pgxc/pgxc.h"
#include "instruments/instr_unique_sql.h"
#include "utils/anls_opt.h"
#include "utils/dynahash.h"
#include "utils/lsyscache.h"
#include "utils/memprot.h"
#include "utils/memutils.h"
#include "utils/selfuncs.h"
#include "utils/syscache.h"
#include "vecexecutor/vechashtable.h"
#include "vectorsonic/vsonicarray.h"
#include "vectorsonic/vsonichash.h"
#include "workload/workload.h"
static void ExecHashIncreaseNumBatches(HashJoinTable hashtable);
static void ExecHashIncreaseNumBuckets(HashJoinTable hashtable);
static void ExecHashBuildSkewHash(HashJoinTable hashtable, Hash* node, int mcvsToUse);
static void ExecHashSkewTableInsert(HashJoinTable hashtable, TupleTableSlot* slot, uint32 hashvalue, int bucketNumber);
static void ExecHashRemoveNextSkewBucket(HashJoinTable hashtable);
static void ExecHashIncreaseBuckets(HashJoinTable hashtable);
static void* dense_alloc(HashJoinTable hashtable, Size size);
/* ----------------------------------------------------------------
* ExecHash
*
* stub for pro forma compliance
* ----------------------------------------------------------------
*/
TupleTableSlot* ExecHash(void)
{
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmodule(MOD_EXECUTOR),
errmsg("Hash node does not support ExecProcNode call convention")));
return NULL;
}
/* ----------------------------------------------------------------
* MultiExecHash
*
* build hash table for hashjoin, doing partitioning if more
* than one batch is required.
* ----------------------------------------------------------------
*/
Node* MultiExecHash(HashState* node)
{
PlanState* outerNode = NULL;
List* hashkeys = NIL;
HashJoinTable hashtable;
TupleTableSlot* slot = NULL;
ExprContext* econtext = NULL;
uint32 hashvalue;
TimestampTz start_time = 0;
/* must provide our own instrumentation support */
if (node->ps.instrument) {
InstrStartNode(node->ps.instrument);
node->hashtable->spill_size = &node->ps.instrument->sorthashinfo.spill_size;
} else {
node->hashtable->spill_size = &node->spill_size;
}
/* init unique sql hash state if needed*/
UpdateUniqueSQLHashStats(NULL, &start_time);
/*
* get state info from node
*/
outerNode = outerPlanState(node);
hashtable = node->hashtable;
/*
* set expression context
*/
hashkeys = node->hashkeys;
econtext = node->ps.ps_ExprContext;
/*
* get all inner tuples and insert into the hash table (or temp files)
*/
WaitState oldStatus = pgstat_report_waitstatus(STATE_EXEC_HASHJOIN_BUILD_HASH);
for (;;) {
slot = ExecProcNode(outerNode);
if (TupIsNull(slot))
break;
/* We have to compute the hash value */
econtext->ecxt_innertuple = slot;
if (ExecHashGetHashValue(hashtable, econtext, hashkeys, false, hashtable->keepNulls, &hashvalue)) {
int bucketNumber;
bucketNumber = ExecHashGetSkewBucket(hashtable, hashvalue);
if (bucketNumber != INVALID_SKEW_BUCKET_NO) {
/* It's a skew tuple, so put it into that hash table */
ExecHashSkewTableInsert(hashtable, slot, hashvalue, bucketNumber);
hashtable->skewTuples += 1;
} else {
/* Not subject to skew optimization, so insert normally */
ExecHashTableInsert(hashtable,
slot,
hashvalue,
node->ps.plan->plan_node_id,
SET_DOP(node->ps.plan->dop),
node->ps.instrument);
}
hashtable->totalTuples += 1;
}
}
(void)pgstat_report_waitstatus(oldStatus);
/* analyze hash table information for unique sql hash state */
UpdateUniqueSQLHashStats(hashtable, &start_time);
/* resize the hash table if needed (NTUP_PER_BUCKET exceeded) */
if (hashtable->nbuckets != hashtable->nbuckets_optimal) {
/* We never decrease the number of buckets. */
Assert(hashtable->nbuckets_optimal > hashtable->nbuckets);
#ifdef HJDEBUG
printf("Increasing nbuckets %d => %d\n", hashtable->nbuckets, hashtable->nbuckets_optimal);
#endif
ExecHashIncreaseNumBuckets(hashtable);
}
/* analysis hash table information created in memory */
if (anls_opt_is_on(ANLS_HASH_CONFLICT))
ExecHashTableStats(hashtable, node->ps.plan->plan_node_id);
/* Account for the buckets in spaceUsed (reported in EXPLAIN ANALYZE) */
hashtable->spaceUsed += hashtable->nbuckets * sizeof(HashJoinTuple);
if (hashtable->spaceUsed > hashtable->spacePeak)
hashtable->spacePeak = hashtable->spaceUsed;
/* must provide our own instrumentation support */
if (node->ps.instrument) {
InstrStopNode(node->ps.instrument, hashtable->totalTuples);
node->ps.instrument->sorthashinfo.nbatch = hashtable->nbatch;
node->ps.instrument->sorthashinfo.nbuckets = hashtable->nbuckets;
node->ps.instrument->sorthashinfo.nbatch_original = hashtable->nbatch_original;
node->ps.instrument->sorthashinfo.spacePeak = hashtable->spacePeak;
if (hashtable->width[0] > 0) {
hashtable->width[1] = hashtable->width[1] / hashtable->width[0];
hashtable->width[0] = -1;
}
node->ps.instrument->width = (int)hashtable->width[1];
node->ps.instrument->sysBusy = hashtable->causedBySysRes;
node->ps.instrument->spreadNum = hashtable->spreadNum;
}
/*
* We do not return the hash table directly because it's not a subtype of
* Node, and so would violate the MultiExecProcNode API. Instead, our
* parent Hashjoin node is expected to know how to fish it out of our node
* state. Ugly but not really worth cleaning up, since Hashjoin knows
* quite a bit more about Hash besides that.
*/
return NULL;
}
/* ----------------------------------------------------------------
* ExecInitHash
*
* Init routine for Hash node
* ----------------------------------------------------------------
*/
HashState* ExecInitHash(Hash* node, EState* estate, int eflags)
{
HashState* hashstate = NULL;
/* check for unsupported flags */
Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
/*
* create state structure
*/
hashstate = makeNode(HashState);
hashstate->ps.plan = (Plan*)node;
hashstate->ps.state = estate;
hashstate->hashtable = NULL;
hashstate->hashkeys = NIL; /* will be set by parent HashJoin */
/*
* Miscellaneous initialization
*
* create expression context for node
*/
ExecAssignExprContext(estate, &hashstate->ps);
/*
* initialize our result slot
*/
ExecInitResultTupleSlot(estate, &hashstate->ps);
/*
* initialize child expressions
*/
hashstate->ps.targetlist = (List*)ExecInitExpr((Expr*)node->plan.targetlist, (PlanState*)hashstate);
hashstate->ps.qual = (List*)ExecInitExpr((Expr*)node->plan.qual, (PlanState*)hashstate);
/*
* initialize child nodes
*/
outerPlanState(hashstate) = ExecInitNode(outerPlan(node), estate, eflags);
/*
* initialize tuple type. no need to initialize projection info because
* this node doesn't do projections
*/
TupleDesc resultDesc = ExecGetResultType(outerPlanState(hashstate));
ExecAssignResultTypeFromTL(&hashstate->ps, resultDesc->tdTableAmType);
hashstate->ps.ps_ProjInfo = NULL;
Assert(hashstate->ps.ps_ResultTupleSlot->tts_tupleDescriptor->tdTableAmType != TAM_INVALID);
return hashstate;
}
/* ---------------------------------------------------------------
* ExecEndHash
*
* clean up routine for Hash node
* ----------------------------------------------------------------
*/
void ExecEndHash(HashState* node)
{
PlanState* outerPlan = NULL;
/*
* free exprcontext
*/
ExecFreeExprContext(&node->ps);
/*
* shut down the subplan
*/
outerPlan = outerPlanState(node);
ExecEndNode(outerPlan);
}
/* ----------------------------------------------------------------
* ExecHashTableCreate
*
* create an empty hashtable data structure for hashjoin.
* ----------------------------------------------------------------
*/
HashJoinTable ExecHashTableCreate(Hash* node, List* hashOperators, bool keepNulls)
{
HashJoinTable hashtable;
Plan* outerNode = NULL;
int nbuckets;
int nbatch;
int num_skew_mcvs;
int log2_nbuckets;
int nkeys;
int i;
int64 local_work_mem = SET_NODEMEM(node->plan.operatorMemKB[0], node->plan.dop);
int64 max_mem = (node->plan.operatorMaxMem > 0) ? SET_NODEMEM(node->plan.operatorMaxMem, node->plan.dop) : 0;
ListCell* ho = NULL;
MemoryContext oldcxt;
/*
* Get information about the size of the relation to be hashed (it's the
* "outer" subtree of this node, but the inner relation of the hashjoin).
* Compute the appropriate size of the hash table.
*/
outerNode = outerPlan(node);
ExecChooseHashTableSize(PLAN_LOCAL_ROWS(outerNode) / SET_DOP(node->plan.dop),
outerNode->plan_width,
OidIsValid(node->skewTable),
&nbuckets,
&nbatch,
&num_skew_mcvs,
local_work_mem);
/*
* If we allows mem auto spread, we should set nbatch to 1 to avoid disk
* spill if estimation from optimizer differs from that from executor
*/
if (node->plan.operatorMaxMem > 0 && nbatch > 1 && nbuckets < INT_MAX / nbatch) {
if (nbuckets * nbatch < (int)(MaxAllocSize / sizeof(HashJoinTuple))) {
nbuckets *= nbatch;
nbatch = 1;
}
}
#ifdef HJDEBUG
printf("nbatch = %d, nbuckets = %d\n", nbatch, nbuckets);
#endif
/* nbuckets must be a power of 2 */
log2_nbuckets = my_log2(nbuckets);
Assert(nbuckets == (1 << log2_nbuckets));
/*
* Initialize the hash table control block.
*
* The hashtable control block is just palloc'd from the executor's
* per-query memory context.
*/
hashtable = (HashJoinTable)palloc(sizeof(HashJoinTableData));
hashtable->nbuckets = nbuckets;
hashtable->nbuckets_original = nbuckets;
hashtable->nbuckets_optimal = nbuckets;
hashtable->log2_nbuckets = log2_nbuckets;
hashtable->log2_nbuckets_optimal = log2_nbuckets;
hashtable->buckets = NULL;
hashtable->keepNulls = keepNulls;
hashtable->skewEnabled = false;
hashtable->skewBucket = NULL;
hashtable->skewBucketLen = 0;
hashtable->nSkewBuckets = 0;
hashtable->skewBucketNums = NULL;
hashtable->nbatch = nbatch;
hashtable->curbatch = 0;
hashtable->nbatch_original = nbatch;
hashtable->nbatch_outstart = nbatch;
hashtable->growEnabled = true;
hashtable->totalTuples = 0;
hashtable->skewTuples = 0;
hashtable->innerBatchFile = NULL;
hashtable->outerBatchFile = NULL;
hashtable->spaceUsed = 0;
hashtable->spacePeak = 0;
hashtable->spill_count = 0;
hashtable->spaceAllowed = local_work_mem * 1024L;
hashtable->spaceUsedSkew = 0;
hashtable->spaceAllowedSkew = hashtable->spaceAllowed * SKEW_WORK_MEM_PERCENT / 100;
hashtable->chunks = NULL;
hashtable->width[0] = hashtable->width[1] = 0;
hashtable->causedBySysRes = false;
/* should we allow auto mem spread in query mem mode? */
hashtable->maxMem = max_mem * 1024L;
hashtable->spreadNum = 0;
/*
* Get info about the hash functions to be used for each hash key. Also
* remember whether the join operators are strict.
*/
nkeys = list_length(hashOperators);
hashtable->outer_hashfunctions = (FmgrInfo*)palloc(nkeys * sizeof(FmgrInfo));
hashtable->inner_hashfunctions = (FmgrInfo*)palloc(nkeys * sizeof(FmgrInfo));
hashtable->hashStrict = (bool*)palloc(nkeys * sizeof(bool));
i = 0;
foreach (ho, hashOperators) {
Oid hashop = lfirst_oid(ho);
Oid left_hashfn;
Oid right_hashfn;
if (!get_op_hash_functions(hashop, &left_hashfn, &right_hashfn))
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_FUNCTION),
errmodule(MOD_EXECUTOR),
errmsg("could not find hash function for hash operator %u", hashop)));
fmgr_info(left_hashfn, &hashtable->outer_hashfunctions[i]);
fmgr_info(right_hashfn, &hashtable->inner_hashfunctions[i]);
hashtable->hashStrict[i] = op_strict(hashop);
i++;
}
/*
* Create temporary memory contexts in which to keep the hashtable working
* storage. See notes in executor/hashjoin.h.
*/
hashtable->hashCxt = AllocSetContextCreate(CurrentMemoryContext,
"HashTableContext",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE,
STANDARD_CONTEXT,
local_work_mem * 1024L);
hashtable->batchCxt = AllocSetContextCreate(hashtable->hashCxt,
"HashBatchContext",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE,
STANDARD_CONTEXT,
local_work_mem * 1024L);
/* Allocate data that will live for the life of the hashjoin */
oldcxt = MemoryContextSwitchTo(hashtable->hashCxt);
if (nbatch > 1) {
/*
* allocate and initialize the file arrays in hashCxt
*/
hashtable->innerBatchFile = (BufFile**)palloc0(nbatch * sizeof(BufFile*));
hashtable->outerBatchFile = (BufFile**)palloc0(nbatch * sizeof(BufFile*));
/* The files will not be opened until needed... */
/* ... but make sure we have temp tablespaces established for them */
PrepareTempTablespaces();
}
/*
* Prepare context for the first-scan space allocations; allocate the
* hashbucket array therein, and set each bucket "empty".
*/
MemoryContextSwitchTo(hashtable->batchCxt);
hashtable->buckets = (HashJoinTuple*)palloc0(nbuckets * sizeof(HashJoinTuple));
/*
* Set up for skew optimization, if possible and there's a need for more
* than one batch. (In a one-batch join, there's no point in it.)
*/
if (nbatch > 1)
ExecHashBuildSkewHash(hashtable, node, num_skew_mcvs);
MemoryContextSwitchTo(oldcxt);
return hashtable;
}
/*
* Compute max tuples which fit into a given mem
*
* HashTable (total of nbuckets)
* [ ] <--hash_header
* [ ]
* [ ]->[ ]->[ ]->....
* [ ]
* [ ]
* [ ]
* ^^^ bucket_bytes
* ^^^^^^^^^^^^^^^inner_rel_bytes
*
* bucket_bytes = hash_header_size * nbuckets
* nbuckets = ntuples/ntuple_per_bucket
* inner_rel_bytes = ntuples * tupsize
* hash_table_bytes = bucket_bytes + inner_rel_bytes;
*
* for a given hash_table_bytes of memory we can most fit in
*
* hash_table_bytes - skew_table_bytes
* ntuples= ------------------------------------------------
* tuple_size + hash_header_size/NTUP_PER_BUCKET
*
* current we don't take max_pointers into account, that will
* give a lower bound of hash_table_max_tuples which is safe
* for us to use.
*
* This is exported so that the planner's costsize.c can use it.
* also refer to ExecChooseHashTableSize
*/
/* Target bucket loading (tuples per bucket) */
#define NTUP_PER_BUCKET 1
double ExecChooseHashTableMaxTuples(int tupwidth, bool useskew, bool vectorized, double hash_table_bytes)
{
int tupsize;
int hash_header_size;
double hash_table_max_tuples;
hash_header_size = vectorized ? sizeof(void*) : sizeof(HashJoinTuple);
if (vectorized) {
tupsize = sizeof(void*) + MAXALIGN(tupwidth);
} else {
tupsize = HJTUPLE_OVERHEAD + MAXALIGN(sizeof(MinimalTupleData)) + MAXALIGN(tupwidth);
}
if (useskew) {
double skew_table_bytes = hash_table_bytes * SKEW_WORK_MEM_PERCENT / 100;
/* ----------
* Divisor is:
* size of a hash tuple +
* worst-case size of skewBucket[] per MCV +
* size of skewBucketNums[] entry +
* size of skew bucket struct itself
* ----------
*/
int num_skew_mcvs =
(int)(skew_table_bytes / (tupsize + (8 * sizeof(HashSkewBucket*)) + sizeof(int) + SKEW_BUCKET_OVERHEAD));
if (num_skew_mcvs > 0) {
hash_table_bytes -= skew_table_bytes;
}
}
hash_table_max_tuples = hash_table_bytes / ((double)tupsize + (double)hash_header_size / NTUP_PER_BUCKET);
return hash_table_max_tuples;
}
/*
* Compute appropriate size for hashtable given the estimated size of the
* relation to be hashed (number of rows and average row width).
*
* This is exported so that the planner's costsize.c can use it.
*/
void ExecChooseHashTableSize(double ntuples, int tupwidth, bool useskew, int* numbuckets, int* numbatches,
int* num_skew_mcvs, int4 localWorkMem, bool vectorized, OpMemInfo* memInfo)
{
int tupsize;
double inner_rel_bytes;
int64 bucket_bytes;
int64 hash_table_bytes;
int64 skew_table_bytes;
int64 max_pointers;
int64 mppow2;
int nbatch = 1;
int nbuckets;
double dbuckets;
int hash_header_size = vectorized ? sizeof(void*) : sizeof(HashJoinTuple);
MEMCTL_LOG(DEBUG2,
"[ExecChooseHashTableSize] ntuples %lf, width %d, useskew: %s, workmem %d, vectorized %s",
ntuples,
tupwidth,
useskew ? "true" : "false",
localWorkMem,
vectorized ? "true" : "false");
/* Force a plausible relation size if no info */
if (ntuples <= 0.0) {
ntuples = 1000.0;
}
/*
* Estimate tupsize based on footprint of tuple in hashtable... note this
* does not allow for any palloc overhead. The manipulations of spaceUsed
* don't count palloc overhead either.
*/
if (vectorized) {
tupsize = sizeof(void*) + MAXALIGN(tupwidth);
} else {
tupsize = HJTUPLE_OVERHEAD + MAXALIGN(sizeof(MinimalTupleData)) + MAXALIGN(tupwidth);
}
inner_rel_bytes = ntuples * tupsize;
/*
* Target in-memory hashtable size is work_mem kilobytes.
*/
hash_table_bytes = localWorkMem * 1024L;
/*
* If skew optimization is possible, estimate the number of skew buckets
* that will fit in the memory allowed, and decrement the assumed space
* available for the main hash table accordingly.
*
* We make the optimistic assumption that each skew bucket will contain
* one inner-relation tuple. If that turns out to be low, we will recover
* at runtime by reducing the number of skew buckets.
*
* hashtable->skewBucket will have up to 8 times as many HashSkewBucket
* pointers as the number of MCVs we allow, since ExecHashBuildSkewHash
* will round up to the next power of 2 and then multiply by 4 to reduce
* collisions.
*/
if (useskew) {
skew_table_bytes = hash_table_bytes * SKEW_WORK_MEM_PERCENT / 100;
/* ----------
* Divisor is:
* size of a hash tuple +
* worst-case size of skewBucket[] per MCV +
* size of skewBucketNums[] entry +
* size of skew bucket struct itself
* ----------
*/
*num_skew_mcvs =
skew_table_bytes / (tupsize + (8 * sizeof(HashSkewBucket*)) + sizeof(int) + SKEW_BUCKET_OVERHEAD);
if (*num_skew_mcvs > 0) {
hash_table_bytes -= skew_table_bytes;
}
} else {
*num_skew_mcvs = 0;
}
/*
* Set nbuckets to achieve an average bucket load of NTUP_PER_BUCKET when
* memory is filled, assuming a single batch; but limit the value so that
* the pointer arrays we'll try to allocate do not exceed work_mem nor
* MaxAllocSize.
*
* Note that both nbuckets and nbatch must be powers of 2 to make
* ExecHashGetBucketAndBatch fast.
*/
max_pointers = (localWorkMem * 1024L) / hash_header_size;
max_pointers = Min(max_pointers, (long)(MaxAllocSize / hash_header_size));
/* If max_pointers isn't a power of 2, must round it down to one */
mppow2 = 1UL << my_log2(max_pointers);
if (max_pointers != mppow2) {
max_pointers = mppow2 / 2;
}
/* Also ensure we avoid integer overflow in nbatch and nbuckets */
/* (this step is redundant given the current value of MaxAllocSize) */
max_pointers = Min(max_pointers, INT_MAX / 2);
dbuckets = ceil(ntuples / NTUP_PER_BUCKET);
dbuckets = Min(dbuckets, max_pointers);
nbuckets = (int)dbuckets;
/* don't let nbuckets be really small, though ... */
nbuckets = Max(nbuckets, MIN_HASH_BUCKET_SIZE);
/* ... and force it to be a power of 2. */
nbuckets = 1 << my_log2(nbuckets);
/*
* If there's not enough space to store the projected number of tuples and
* the required bucket headers, we will need multiple batches.
*/
bucket_bytes = ((int64)hash_header_size) * nbuckets;
if (memInfo != NULL) {
memInfo->maxMem = (inner_rel_bytes + bucket_bytes) / 1024L;
}
if (inner_rel_bytes + bucket_bytes > hash_table_bytes) {
/* We'll need multiple batches */
int64 lbuckets;
double dbatch;
int minbatch;
double max_batch;
int64 bucket_size;
/*
* Estimate the number of buckets we'll want to have when work_mem is
* entirely full. Each bucket will contain a bucket pointer plus
* NTUP_PER_BUCKET tuples, whose projected size already includes
* overhead for the hash code, pointer to the next tuple, etc.
*/
bucket_size = ((int64)tupsize * NTUP_PER_BUCKET + hash_header_size);
lbuckets = 1UL << my_log2(hash_table_bytes / bucket_size);
lbuckets = Min(lbuckets, max_pointers);
nbuckets = (int)lbuckets;
nbuckets = 1 << my_log2(nbuckets);
bucket_bytes = (int64)nbuckets * hash_header_size;
/*
* Buckets are simple pointers to hashjoin tuples, while tupsize
* includes the pointer, hash code, and MinimalTupleData. So buckets
* should never really exceed 25% of work_mem (even for
* NTUP_PER_BUCKET=1); except maybe for work_mem values that are not
* 2^N bytes, where we might get more because of doubling. So let's
* look for 50% here.
*/
Assert(bucket_bytes <= hash_table_bytes / 2);
/* Calculate required number of batches. */
dbatch = ceil(inner_rel_bytes / (hash_table_bytes - bucket_bytes));
dbatch = Min(dbatch, max_pointers);
minbatch = (int)dbatch;
nbatch = 2;
while (nbatch < minbatch) {
nbatch <<= 1;
}
/*
* This Min() steps limit the nbatch so that the pointer arrays
* we'll try to allocate do not exceed MaxAllocSize.
*/
max_batch = (MaxAllocSize + 1) / sizeof(BufFile*) / 2;
nbatch = (int)Min(nbatch, max_batch);
}
Assert(nbuckets > 0);
Assert(nbatch > 0);
*numbuckets = nbuckets;
*numbatches = nbatch;
MEMCTL_LOG(DEBUG2, "[ExecChooseHashTableSize] nbuckets: %d, nbatch: %d", nbuckets, nbatch);
}
/*
* Get typeSize of the input typeOid and typeMod.
* Some special adjustment for hashkey col.
*/
int ExecSonicHashGetAtomTypeSize(Oid typeOid, int typeMod, bool isHashKey)
{
int minlen;
int atomTypeSize;
minlen = getDataMinLen(typeOid, typeMod);
if (!COL_IS_ENCODE(typeOid)) {
atomTypeSize = minlen;
if (typeOid == TIDOID)
atomTypeSize = 8;
} else if (minlen == -1) {
atomTypeSize = sizeof(Datum);
} else {
atomTypeSize = minlen;
}
/*
* These hashKey cols are a little special, which is one of these typeOid:
* SONIC_CHAR_DIC_TYPE, SONIC_FIXLEN_TYPE, SONIC_NUMERIC_COMPRESS_TYPE.
* Because they store them as pointer. Thus, do some adjustment.
*/
if (isHashKey && ((minlen > 8 && minlen <= 16) || typeOid == BPCHAROID || typeOid == CHAROID)) {
atomTypeSize = sizeof(Datum);
}
return atomTypeSize;
}
/*
* Compute m_arr size according to atomTypeSize
*/
int64 ExecSonicHashGetAtomArrayBytes(
double ntuples, int m_arrSize, int m_atomSize, int64 atomTypeSize, bool hasNullFlag)
{
int64 atomItemNum;
int64 atomFlagSize;
int64 atom_array_bytes;
atomItemNum = m_atomSize * ((int64)ntuples / m_atomSize + 1);
atomFlagSize = hasNullFlag ? ((atomItemNum + 7) / 8) : 0;
atom_array_bytes = m_arrSize * sizeof(void*) + atomItemNum * atomTypeSize + atomFlagSize;
return atom_array_bytes;
}
/*
* Estimate hash bucket typeSize related to nbuckets
*/
uint8 EstimateBucketTypeSize(int nbuckets)
{
uint8 bucketTypeSize;
if ((((uint64)nbuckets) & 0xffff) == ((uint64)nbuckets)) {
bucketTypeSize = sizeof(uint16); // 2 bytes
} else if ((((uint64)nbuckets) & 0xffffffff) == ((uint64)nbuckets)) {
bucketTypeSize = sizeof(uint32); // 4 byttes
} else {
bucketTypeSize = sizeof(uint64); // 8 bytes
}
return bucketTypeSize;
}
/*
* Compute appropriate size for hashtable given the estimated size of the
* relation to be hashed (number of rows).
*/
void ExecChooseSonicHashTableSize(Path* inner_path, List* hashclauses, int* inner_width, bool isComplicateHashKey,
int* numbuckets, int* numbatches, int4 localWorkMem, OpMemInfo* memInfo, int dop)
{
ListCell* lc = NULL;
Var* var = NULL;
Node* innerkey = NULL;
int64 atomTypeSize;
int m_arrSize;
int m_atomSize;
int64 hash_data_bytes = 0;
int nbatch = 1;
int64 nbuckets;
int64 mppow2;
int m_bucketTypeSize;
int64 hash_bucket_bytes;
int64 hash_table_bytes;
int tuple_width = 0;
double ntuples = PATH_LOCAL_ROWS(inner_path) / dop;
List* tleList = inner_path->parent->reltargetlist;
Relids inner_relids = inner_path->parent->relids;
MEMCTL_LOG(
DEBUG2, "[ExecChooseHashTableSize] ntuples %lf, workmem %d, vectorized %s", ntuples, localWorkMem, "true");
/* Force a plausible relation size if no info */
if (ntuples <= 0.0) {
ntuples = 1000.0;
}
hash_table_bytes = localWorkMem * 1024L;
/* Estimate atomTypeSize for each col and caculate in-memory data size in hashtable*/
m_atomSize = INIT_DATUM_ARRAY_SIZE;
m_arrSize = ((int64)ntuples / (m_atomSize * INIT_ARR_CONTAINER_SIZE) + 1) * INIT_ARR_CONTAINER_SIZE;
if (!isComplicateHashKey && list_length(hashclauses) == 1) {
RestrictInfo* restrictinfo = (RestrictInfo*)lfirst(list_head(hashclauses));
if (bms_is_subset(restrictinfo->right_relids, inner_relids)) {
innerkey = get_rightop(restrictinfo->clause);
} else {
Assert(bms_is_subset(restrictinfo->left_relids, inner_relids));
innerkey = get_leftop(restrictinfo->clause);
}
}
foreach (lc, tleList) {
var = (Var*)lfirst(lc);
/* Check whether the current target entry is hashKey or not. */
if (innerkey != NULL && IsA(innerkey, Var) && equal((Var*)innerkey, var)) {
atomTypeSize = ExecSonicHashGetAtomTypeSize(var->vartype, var->vartypmod, true);
} else {
atomTypeSize = ExecSonicHashGetAtomTypeSize(var->vartype, var->vartypmod, false);
}
tuple_width += atomTypeSize;
hash_data_bytes += ExecSonicHashGetAtomArrayBytes(ntuples, m_arrSize, m_atomSize, atomTypeSize, true);
}
/* Complicate hashkey needs m_hash defined as SonicDatumArray type */
if (isComplicateHashKey) {
tuple_width += sizeof(uint32);
hash_data_bytes += ExecSonicHashGetAtomArrayBytes(ntuples, m_arrSize, m_atomSize, sizeof(uint32), false);
}
*inner_width = tuple_width;
/* Estimate bucket number.*/
#ifdef USE_PRIME
nbuckets = (int64)hashfindprime((uint64)ntuples);
#else
nbuckets = (int64)Min(ntuples, MAX_BUCKET_NUM);
/*
* Ensure nbuckets is not too small.
* Note: e must round nbuckets down to one if it is not a power of 2.
* Similar to getPower2LessNum().
*/
mppow2 = 1L << my_log2(nbuckets);
if (nbuckets != mppow2)
nbuckets = mppow2 / 2;
nbuckets = Max(nbuckets, MIN_HASH_TABLE_SIZE);
#endif
/* Estimate the size of m_bucket type*/
m_bucketTypeSize = EstimateBucketTypeSize(nbuckets);
/* Caculate bucket size*/
hash_bucket_bytes = m_bucketTypeSize * nbuckets;
/*
* Record ideal memory usage without disk.
* That is, the size of hash table including the data size and bucket size.
*/
if (memInfo != NULL) {
memInfo->maxMem = (double)((hash_data_bytes + hash_bucket_bytes) / 1024L);
}
/* Target in-memory hashtable size is work_mem kilobytes. */
if (hash_data_bytes + hash_bucket_bytes > hash_table_bytes) {
/* We'll need multiple batches */
double dbatch;
int64 maxbucket;
int minbatch;
double maxbatch;
maxbucket =
Min(hash_table_bytes / ((long)m_bucketTypeSize + BUCKET_OVERHEAD), (long)(MaxAllocSize / m_bucketTypeSize));
#ifdef USE_PRIME
nbuckets = (int64)Min(maxbucket, (int64)hashfindprime((uint64)ntuples));
#else
nbuckets = Min(maxbucket, max_pointers);
#endif
mppow2 = 1UL << my_log2(nbuckets);
if (nbuckets != mppow2)
nbuckets = mppow2 / 2;
hash_bucket_bytes = nbuckets * m_bucketTypeSize;
Assert(hash_bucket_bytes <= hash_table_bytes / 2);
/* Calculate required number of batches. */
dbatch = ceil(hash_data_bytes / (hash_table_bytes - hash_bucket_bytes));
dbatch = Min(dbatch, maxbucket);
minbatch = (int)dbatch;
nbatch = 2;
while (nbatch < minbatch) {
nbatch <<= 1;
}
/*
* This Min() steps limit the nbatch so that the pointer arrays
* we'll try to allocate do not exceed MaxAllocSize.
*/
maxbatch = (MaxAllocSize + 1) / sizeof(BufFile*) / 2;
nbatch = (int)Min(nbatch, maxbatch);
}
Assert(nbuckets > 0);
Assert(nbatch > 0);
*numbuckets = nbuckets;
*numbatches = nbatch;
MEMCTL_LOG(DEBUG2, "[ExecChooseSonicHashTableSize] nbuckets: %ld, nbatch: %d", nbuckets, nbatch);
}
/* ----------------------------------------------------------------
* ExecHashTableDestroy
*
* destroy a hash table
* ----------------------------------------------------------------
*/
void ExecHashTableDestroy(HashJoinTable hashtable)
{
int i;
/*
* Make sure all the temp files are closed. We skip batch 0, since it
* can't have any temp files (and the arrays might not even exist if
* nbatch is only 1).
*/
for (i = 1; i < hashtable->nbatch; i++) {
if (hashtable->innerBatchFile[i])
BufFileClose(hashtable->innerBatchFile[i]);
if (hashtable->outerBatchFile[i])
BufFileClose(hashtable->outerBatchFile[i]);
}
/* Free the unused buffers */
pfree_ext(hashtable->outer_hashfunctions);
pfree_ext(hashtable->inner_hashfunctions);
pfree_ext(hashtable->hashStrict);
/* Release working memory (batchCxt is a child, so it goes away too) */
MemoryContextDelete(hashtable->hashCxt);
/* And drop the control block */
pfree_ext(hashtable);
}
/*
* ExecHashIncreaseNumBatches
* increase the original number of batches in order to reduce
* current memory consumption
*/
static void ExecHashIncreaseNumBatches(HashJoinTable hashtable)
{
int oldnbatch = hashtable->nbatch;
int curbatch = hashtable->curbatch;
int nbatch;
MemoryContext oldcxt;
long ninmemory;
long nfreed;
HashMemoryChunk oldchunks;
errno_t rc;
/* do nothing if we've decided to shut off growth */
if (!hashtable->growEnabled)
return;
/* safety check to avoid overflow */
if ((uint32)oldnbatch > Min(INT_MAX / 2, MaxAllocSize / (sizeof(void*) * 2)))
return;
nbatch = oldnbatch * 2;
Assert(nbatch > 1);
#ifdef HJDEBUG
printf("Increasing nbatch to %d because space = %lu\n", nbatch, (unsigned long)hashtable->spaceUsed);
#endif
oldcxt = MemoryContextSwitchTo(hashtable->hashCxt);
if (hashtable->innerBatchFile == NULL) {
/* we had no file arrays before */
hashtable->innerBatchFile = (BufFile**)palloc0(nbatch * sizeof(BufFile*));
hashtable->outerBatchFile = (BufFile**)palloc0(nbatch * sizeof(BufFile*));
/* time to establish the temp tablespaces, too */
PrepareTempTablespaces();
} else {
/* enlarge arrays and zero out added entries */
hashtable->innerBatchFile = (BufFile**)repalloc(hashtable->innerBatchFile, nbatch * sizeof(BufFile*));
hashtable->outerBatchFile = (BufFile**)repalloc(hashtable->outerBatchFile, nbatch * sizeof(BufFile*));
rc = memset_s(hashtable->innerBatchFile + oldnbatch,
(nbatch - oldnbatch) * sizeof(BufFile*),
0,
(nbatch - oldnbatch) * sizeof(BufFile*));
securec_check(rc, "\0", "\0");
rc = memset_s(hashtable->outerBatchFile + oldnbatch,
(nbatch - oldnbatch) * sizeof(BufFile*),
0,
(nbatch - oldnbatch) * sizeof(BufFile*));
securec_check(rc, "\0", "\0");
}
MemoryContextSwitchTo(oldcxt);
hashtable->nbatch = nbatch;
/*
* Scan through the existing hash table entries and dump out any that are
* no longer of the current batch.
*/
ninmemory = nfreed = 0;
/* If know we need to resize nbuckets, we can do it while rebatching. */
if (hashtable->nbuckets_optimal != hashtable->nbuckets) {
/* we never decrease the number of buckets */
Assert(hashtable->nbuckets_optimal > hashtable->nbuckets);
hashtable->nbuckets = hashtable->nbuckets_optimal;
hashtable->log2_nbuckets = hashtable->log2_nbuckets_optimal;
hashtable->buckets = (struct HashJoinTupleData**) repalloc(
hashtable->buckets, sizeof(HashJoinTuple) * hashtable->nbuckets);
}
/*
* We will scan through the chunks directly, so that we can reset the
* buckets now and not have to keep track which tuples in the buckets have
* already been processed. We will free the old chunks as we go.
*/
rc = memset_s(hashtable->buckets,
sizeof(HashJoinTuple) * hashtable->nbuckets,
0,
sizeof(HashJoinTuple) * hashtable->nbuckets);
securec_check(rc, "\0", "\0");
oldchunks = hashtable->chunks;
hashtable->chunks = NULL;
/* so, let's scan through the old chunks, and all tuples in each chunk */
while (oldchunks != NULL) {
HashMemoryChunk nextchunk = oldchunks->next;
/* position within the buffer (up to oldchunks->used) */
size_t idx = 0;
/* process all tuples stored in this chunk (and then free it) */
while (idx < oldchunks->used) {
HashJoinTuple hashTuple = (HashJoinTuple)(oldchunks->data + idx);
MinimalTuple tuple = HJTUPLE_MINTUPLE(hashTuple);
int hashTupleSize = (HJTUPLE_OVERHEAD + tuple->t_len);
int bucketno;
int batchno;
ninmemory++;
ExecHashGetBucketAndBatch(hashtable, hashTuple->hashvalue, &bucketno, &batchno);
if (batchno == curbatch) {
/* keep tuple in memory - copy it into the new chunk */
HashJoinTuple copyTuple = (HashJoinTuple)dense_alloc(hashtable, hashTupleSize);
rc = memcpy_s(copyTuple, hashTupleSize, hashTuple, hashTupleSize);
securec_check(rc, "\0", "\0");
/* and add it back to the appropriate bucket */
copyTuple->next = hashtable->buckets[bucketno];
hashtable->buckets[bucketno] = copyTuple;
} else {
/* dump it out */
Assert(batchno > curbatch);
ExecHashJoinSaveTuple(
HJTUPLE_MINTUPLE(hashTuple), hashTuple->hashvalue, &hashtable->innerBatchFile[batchno]);
hashtable->spaceUsed -= hashTupleSize;
nfreed++;
}
/* next tuple in this chunk */
idx += MAXALIGN(hashTupleSize);
/* allow this loop to be cancellable */
CHECK_FOR_INTERRUPTS();
}
/* we're done with this chunk - free it and proceed to the next one */
pfree_ext(oldchunks);
oldchunks = nextchunk;
}
#ifdef HJDEBUG
printf("Freed %ld of %ld tuples, space now %lu\n", nfreed, ninmemory, (unsigned long)hashtable->spaceUsed);
#endif
/*
* If we dumped out either all or none of the tuples in the table, disable
* further expansion of nbatch. This situation implies that we have
* enough tuples of identical hashvalues to overflow spaceAllowed.
* Increasing nbatch will not fix it since there's no way to subdivide the
* group any more finely. We have to just gut it out and hope the server
* has enough RAM.
*/
if (nfreed == 0 || nfreed == ninmemory) {
hashtable->growEnabled = false;
#ifdef HJDEBUG
printf("Disabling further increase of nbatch\n");
#endif
}
}
/*
* ExecHashIncreaseNumBuckets
* increase the original number of buckets in order to reduce
* number of tuples per bucket
*/
static void ExecHashIncreaseNumBuckets(HashJoinTable hashtable)
{
HashMemoryChunk chunk;
errno_t rc;
/* do nothing if not an increase (it's called increase for a reason) */
if (hashtable->nbuckets >= hashtable->nbuckets_optimal)
return;
/*
* We already know the optimal number of buckets, so let's just
* compute the log2_nbuckets for it.
*/
hashtable->nbuckets = hashtable->nbuckets_optimal;
hashtable->log2_nbuckets = my_log2(hashtable->nbuckets_optimal);
Assert(hashtable->nbuckets > 1);
Assert(hashtable->nbuckets <= (INT_MAX / 2));
Assert(hashtable->nbuckets == (1 << hashtable->log2_nbuckets));
#ifdef HJDEBUG
printf("Increasing nbuckets to %d\n", hashtable->nbuckets);
#endif
/*
* Just reallocate the proper number of buckets - we don't need to
* walk through them - we can walk the dense-allocated chunks
* (just like in ExecHashIncreaseNumBatches, but without all the
* copying into new chunks)
*/
hashtable->buckets = (HashJoinTuple *)repalloc(hashtable->buckets, hashtable->nbuckets * sizeof(HashJoinTuple));
rc = memset_s(hashtable->buckets,
sizeof(void *) * hashtable->nbuckets,
0,
sizeof(void *) * hashtable->nbuckets);
securec_check(rc, "\0", "\0");
/* scan through all tuples in all chunks to rebuild the hash table */
for (chunk = hashtable->chunks; chunk != NULL; chunk = chunk->next) {
/* process all tuples stored in this chunk */
size_t idx = 0;
while (idx < chunk->used) {
HashJoinTuple hashTuple = (HashJoinTuple)(chunk->data + idx);
int bucketno;
int batchno;
ExecHashGetBucketAndBatch(hashtable, hashTuple->hashvalue, &bucketno, &batchno);
/* add the tuple to the proper bucket */
hashTuple->next = hashtable->buckets[bucketno];
hashtable->buckets[bucketno] = hashTuple;
/* advance index past the tuple */
idx += MAXALIGN(HJTUPLE_OVERHEAD + HJTUPLE_MINTUPLE(hashTuple)->t_len);
}
}
#ifdef HJDEBUG
printf("Nbuckets increased to %d, average items per bucket %.1f\n", hashtable->nbuckets,
batchTuples / hashtable->nbuckets);
#endif
}
/*
* ExecHashTableInsert
* insert a tuple into the hash table depending on the hash value
* it may just go to a temp file for later batches
*
* Note: the passed TupleTableSlot may contain a regular, minimal, or virtual
* tuple; the minimal case in particular is certain to happen while reloading
* tuples from batch files. We could save some cycles in the regular-tuple
* case by not forcing the slot contents into minimal form; not clear if it's
* worth the messiness required.
*/
void ExecHashTableInsert(
HashJoinTable hashtable, TupleTableSlot* slot, uint32 hashvalue, int planid, int dop, Instrumentation* instrument)
{
MinimalTuple tuple = ExecFetchSlotMinimalTuple(slot);
int bucketno;
int batchno;
errno_t errorno = EOK;
ExecHashGetBucketAndBatch(hashtable, hashvalue, &bucketno, &batchno);
/*
* decide whether to put the tuple in the hash table or a temp file
*/
if (batchno == hashtable->curbatch) {
/*
* put the tuple in hash table
*/
HashJoinTuple hashTuple;
int hashTupleSize;
double ntuples = (hashtable->totalTuples - hashtable->skewTuples);
/* Create the HashJoinTuple */
hashTupleSize = HJTUPLE_OVERHEAD + tuple->t_len;
hashTuple = (HashJoinTuple)dense_alloc(hashtable, hashTupleSize);
hashTuple->hashvalue = hashvalue;
errorno = memcpy_s(HJTUPLE_MINTUPLE(hashTuple), tuple->t_len, tuple, tuple->t_len);
securec_check(errorno, "\0", "\0");
/*
* We always reset the tuple-matched flag on insertion. This is okay
* even when reloading a tuple from a batch file, since the tuple
* could not possibly have been matched to an outer tuple before it
* went into the batch file.
*/
HeapTupleHeaderClearMatch(HJTUPLE_MINTUPLE(hashTuple));
/* Push it onto the front of the bucket's list */
hashTuple->next = hashtable->buckets[bucketno];
hashtable->buckets[bucketno] = hashTuple;
/* Record the total width and total tuples for first batch until spill */
if (hashtable->width[0] >= 0) {
hashtable->width[0]++;
hashtable->width[1] += tuple->t_len;
}
/*
* Increase the (optimal) number of buckets if we just exceeded the
* NTUP_PER_BUCKET threshold, but only when there's still a single batch.
*/
if ((hashtable->nbatch == 1) && (hashtable->nbuckets_optimal <= INT_MAX / 2) && /* overflow protection */
(ntuples >= (hashtable->nbuckets_optimal * NTUP_PER_BUCKET))) {
hashtable->nbuckets_optimal *= 2;
hashtable->log2_nbuckets_optimal += 1;
}
/* Account for space used, and back off if we've used too much */
hashtable->spaceUsed += hashTupleSize;
if (hashtable->spaceUsed > hashtable->spacePeak) {
hashtable->spacePeak = hashtable->spaceUsed;
}
bool sysBusy = gs_sysmemory_busy(hashtable->spaceUsed * dop, false);
if (hashtable->spaceUsed + int64(hashtable->nbuckets_optimal * sizeof(HashJoinTuple)) > hashtable->spaceAllowed
|| sysBusy) {
AllocSetContext* set = (AllocSetContext*)(hashtable->hashCxt);
if (sysBusy) {
hashtable->causedBySysRes = true;
hashtable->spaceAllowed = hashtable->spaceUsed;
set->maxSpaceSize = hashtable->spaceUsed;
/* if hashtable failed to grow, this branch can be kicked many times */
if (hashtable->growEnabled) {
MEMCTL_LOG(LOG,
"HashJoin(%d) early spilled, workmem: %ldKB, usedmem: %ldKB",
planid,
hashtable->spaceAllowed / 1024L,
hashtable->spaceUsed / 1024L);
pgstat_add_warning_early_spill();
}
/* try to auto spread memory if possible */
} else if (hashtable->curbatch == 0 && hashtable->maxMem > hashtable->spaceAllowed) {
hashtable->spaceAllowed = hashtable->spaceUsed;
int64 spreadMem = Min(Min(dywlm_client_get_memory() * 1024L, hashtable->spaceAllowed),
hashtable->maxMem - hashtable->spaceAllowed);
if (spreadMem > hashtable->spaceAllowed * MEM_AUTO_SPREAD_MIN_RATIO) {
hashtable->spaceAllowed += spreadMem;
hashtable->spreadNum++;
ExecHashIncreaseBuckets(hashtable);
set->maxSpaceSize += spreadMem;
MEMCTL_LOG(DEBUG2,
"HashJoin(%d) auto mem spread %ldKB succeed, and work mem is %ldKB.",
planid,
spreadMem / 1024L,
hashtable->spaceAllowed / 1024L);
return;
}
/* if hashtable failed to grow, this branch can be kicked many times */
if (hashtable->growEnabled) {
MEMCTL_LOG(LOG,
"HashJoin(%d) auto mem spread %ldKB failed, and work mem is %ldKB.",
planid,
spreadMem / 1024L,
hashtable->spaceAllowed / 1024L);
if (hashtable->spreadNum) {
pgstat_add_warning_spill_on_memory_spread();
}
}
}
/* cache the memory size into instrument for explain performance */
if (instrument != NULL) {
instrument->memoryinfo.peakOpMemory = hashtable->spaceUsed;
}
if (hashtable->width[0] > 0)
hashtable->width[1] = hashtable->width[1] / hashtable->width[0];
hashtable->width[0] = -1;
ExecHashIncreaseNumBatches(hashtable);
}
} else {
/*
* put the tuple into a temp file for later batches
*/
Assert(batchno > hashtable->curbatch);
ExecHashJoinSaveTuple(tuple, hashvalue, &hashtable->innerBatchFile[batchno]);
hashtable->spill_count += 1;
*hashtable->spill_size += sizeof(uint32) + tuple->t_len;
pgstat_increase_session_spill_size(sizeof(uint32) + tuple->t_len);
}
}
/*
* ExecHashGetHashValue
* Compute the hash value for a tuple
*
* The tuple to be tested must be in either econtext->ecxt_outertuple or
* econtext->ecxt_innertuple. Vars in the hashkeys expressions should have
* varno either OUTER_VAR or INNER_VAR.
*
* A TRUE result means the tuple's hash value has been successfully computed
* and stored at *hashvalue. A FALSE result means the tuple cannot match
* because it contains a null attribute, and hence it should be discarded
* immediately. (If keep_nulls is true then FALSE is never returned.)
*/
bool ExecHashGetHashValue(HashJoinTable hashtable, ExprContext* econtext, List* hashkeys, bool outer_tuple,
bool keep_nulls, uint32* hashvalue)
{
uint32 hashkey = 0;
FmgrInfo* hashfunctions = NULL;
ListCell* hk = NULL;
int i = 0;
MemoryContext oldContext;
/*
* We reset the eval context each time to reclaim any memory leaked in the
* hashkey expressions.
*/
ResetExprContext(econtext);
oldContext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
if (outer_tuple)
hashfunctions = hashtable->outer_hashfunctions;
else
hashfunctions = hashtable->inner_hashfunctions;
foreach (hk, hashkeys) {
ExprState* keyexpr = (ExprState*)lfirst(hk);
Datum keyval;
bool isNull = false;
/* rotate hashkey left 1 bit at each step */
hashkey = (hashkey << 1) | ((hashkey & 0x80000000) ? 1 : 0);
/*
* Get the join attribute value of the tuple
*/
keyval = ExecEvalExpr(keyexpr, econtext, &isNull, NULL);
/*
* If the attribute is NULL, and the join operator is strict, then
* this tuple cannot pass the join qual so we can reject it
* immediately (unless we're scanning the outside of an outer join, in
* which case we must not reject it). Otherwise we act like the
* hashcode of NULL is zero (this will support operators that act like
* IS NOT DISTINCT, though not any more-random behavior). We treat
* the hash support function as strict even if the operator is not.
*
* Note: currently, all hashjoinable operators must be strict since
* the hash index AM assumes that. However, it takes so little extra
* code here to allow non-strict that we may as well do it.
*/
if (isNull) {
if (hashtable->hashStrict[i] && !keep_nulls) {
MemoryContextSwitchTo(oldContext);
return false; /* cannot match */
}
/* else, leave hashkey unmodified, equivalent to hashcode 0 */
} else {
/* Compute the hash function */
uint32 hkey;
hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i], keyval));
hashkey ^= hkey;
}
i++;
}
MemoryContextSwitchTo(oldContext);
hashkey = DatumGetUInt32(hash_uint32(hashkey));
*hashvalue = hashkey;
return true;
}
/*
* ExecHashGetBucketAndBatch
* Determine the bucket number and batch number for a hash value
*
* Note: on-the-fly increases of nbatch must not change the bucket number
* for a given hash code (since we don't move tuples to different hash
* chains), and must only cause the batch number to remain the same or
* increase. Our algorithm is
* bucketno = hashvalue MOD nbuckets
* batchno = (hashvalue DIV nbuckets) MOD nbatch
* where nbuckets and nbatch are both expected to be powers of 2, so we can
* do the computations by shifting and masking. (This assumes that all hash
* functions are good about randomizing all their output bits, else we are
* likely to have very skewed bucket or batch occupancy.)
*
* nbuckets and log2_nbuckets may change while nbatch == 1 because of dynamic
* bucket count growth. Once we start batching, the value is fixed and does
* not change over the course of the join (making it possible to compute batch
* number the way we do here).
*
* nbatch is always a power of 2; we increase it only by doubling it. This
* effectively adds one more bit to the top of the batchno.
*/
void ExecHashGetBucketAndBatch(HashJoinTable hashtable, uint32 hashvalue, int* bucketno, int* batchno)
{
uint32 nbuckets = (uint32)hashtable->nbuckets;
uint32 nbatch = (uint32)hashtable->nbatch;
if (nbatch > 1) {
/* we can do MOD by masking, DIV by shifting */
*bucketno = hashvalue & (nbuckets - 1);
*batchno = (hashvalue >> hashtable->log2_nbuckets) & (nbatch - 1);
} else {
*bucketno = hashvalue & (nbuckets - 1);
*batchno = 0;
}
}
/*
* ExecScanHashBucket
* scan a hash bucket for matches to the current outer tuple
*
* The current outer tuple must be stored in econtext->ecxt_outertuple.
*
* On success, the inner tuple is stored into hjstate->hj_CurTuple and
* econtext->ecxt_innertuple, using hjstate->hj_HashTupleSlot as the slot
* for the latter.
*/
bool ExecScanHashBucket(HashJoinState* hjstate, ExprContext* econtext)
{
List* hjclauses = hjstate->hashclauses;
HashJoinTable hashtable = hjstate->hj_HashTable;
HashJoinTuple hashTuple = hjstate->hj_CurTuple;
uint32 hashvalue = hjstate->hj_CurHashValue;
/*
* hj_CurTuple is the address of the tuple last returned from the current
* bucket, or NULL if it's time to start scanning a new bucket.
*
* If the tuple hashed to a skew bucket then scan the skew bucket
* otherwise scan the standard hashtable bucket.
*/
if (hashTuple != NULL)
hashTuple = hashTuple->next;
else if (hjstate->hj_CurSkewBucketNo != INVALID_SKEW_BUCKET_NO)
hashTuple = hashtable->skewBucket[hjstate->hj_CurSkewBucketNo]->tuples;
else
hashTuple = hashtable->buckets[hjstate->hj_CurBucketNo];
while (hashTuple != NULL) {
if (hashTuple->hashvalue == hashvalue) {
TupleTableSlot* inntuple = NULL;
/* insert hashtable's tuple into exec slot so ExecQual sees it */
inntuple =
ExecStoreMinimalTuple(HJTUPLE_MINTUPLE(hashTuple), hjstate->hj_HashTupleSlot, false); /* do not pfree */
econtext->ecxt_innertuple = inntuple;
/* reset temp memory each time to avoid leaks from qual expr */
ResetExprContext(econtext);
/* we allow null = null in special case, so an additional judgement is needed*/
if (ExecQual(hjclauses, econtext, false) ||
(hjstate->js.nulleqqual != NIL && ExecQual(hjstate->js.nulleqqual, econtext, false))) {
hjstate->hj_CurTuple = hashTuple;
return true;
}
}
/*
* For right Semi/Anti join, we delete mathced tuples in HashTable to make next matching faster,
* so pointer hj_PreTuple is designed to follow the hj_CurTuple and to help us to clear the HashTable.
*/
if (hjstate->js.jointype == JOIN_RIGHT_SEMI || hjstate->js.jointype == JOIN_RIGHT_ANTI)
hjstate->hj_PreTuple = hashTuple;
hashTuple = hashTuple->next;
}
/*
* no match
*/
return false;
}
/*
* ExecPrepHashTableForUnmatched
* set up for a series of ExecScanHashTableForUnmatched calls
*/
void ExecPrepHashTableForUnmatched(HashJoinState* hjstate)
{
/*
* ---------- During this scan we use the HashJoinState fields as follows:
*
* hj_CurBucketNo: next regular bucket to scan hj_CurSkewBucketNo: next
* skew bucket (an index into skewBucketNums) hj_CurTuple: last tuple
* returned, or NULL to start next bucket ----------
*/
hjstate->hj_CurBucketNo = 0;
hjstate->hj_CurSkewBucketNo = 0;
hjstate->hj_CurTuple = NULL;
}
/*
* ExecScanHashTableForUnmatched
* scan the hash table for unmatched inner tuples
*
* On success, the inner tuple is stored into hjstate->hj_CurTuple and
* econtext->ecxt_innertuple, using hjstate->hj_HashTupleSlot as the slot
* for the latter.
*/
bool ExecScanHashTableForUnmatched(HashJoinState* hjstate, ExprContext* econtext)
{
HashJoinTable hashtable = hjstate->hj_HashTable;
HashJoinTuple hashTuple = hjstate->hj_CurTuple;
for (;;) {
/*
* hj_CurTuple is the address of the tuple last returned from the
* current bucket, or NULL if it's time to start scanning a new
* bucket.
*/
if (hashTuple != NULL)
hashTuple = hashTuple->next;
else if (hjstate->hj_CurBucketNo < hashtable->nbuckets) {
hashTuple = hashtable->buckets[hjstate->hj_CurBucketNo];
hjstate->hj_CurBucketNo++;
} else if (hjstate->hj_CurSkewBucketNo < hashtable->nSkewBuckets) {
int j = hashtable->skewBucketNums[hjstate->hj_CurSkewBucketNo];
hashTuple = hashtable->skewBucket[j]->tuples;
hjstate->hj_CurSkewBucketNo++;
} else
break; /* finished all buckets */
while (hashTuple != NULL) {
if (!HeapTupleHeaderHasMatch(HJTUPLE_MINTUPLE(hashTuple))) {
TupleTableSlot* inntuple = NULL;
/* insert hashtable's tuple into exec slot */
inntuple = ExecStoreMinimalTuple(
HJTUPLE_MINTUPLE(hashTuple), hjstate->hj_HashTupleSlot, false); /* do not pfree */
econtext->ecxt_innertuple = inntuple;
/*
* Reset temp memory each time; although this function doesn't
* do any qual eval, the caller will, so let's keep it
* parallel to ExecScanHashBucket.
*/
ResetExprContext(econtext);
hjstate->hj_CurTuple = hashTuple;
return true;
}
hashTuple = hashTuple->next;
}
}
/*
* no more unmatched tuples
*/
return false;
}
/*
* ExecHashTableReset
*
* reset hash table header for new batch
*/
void ExecHashTableReset(HashJoinTable hashtable)
{
MemoryContext oldcxt;
int nbuckets = hashtable->nbuckets;
/*
* Release all the hash buckets and tuples acquired in the prior pass, and
* reinitialize the context for a new pass.
*/
MemoryContextReset(hashtable->batchCxt);
oldcxt = MemoryContextSwitchTo(hashtable->batchCxt);
/* Reallocate and reinitialize the hash bucket headers. */
hashtable->buckets = (HashJoinTuple*)palloc0(nbuckets * sizeof(HashJoinTuple));
hashtable->spaceUsed = 0;
MemoryContextSwitchTo(oldcxt);
/* Forget the chunks (the memory was freed by the context reset above). */
hashtable->chunks = NULL;
}
/*
* ExecHashTableResetMatchFlags
* Clear all the HeapTupleHeaderHasMatch flags in the table
*/
void ExecHashTableResetMatchFlags(HashJoinTable hashtable)
{
HashJoinTuple tuple;
int i;
/* Reset all flags in the main table ... */
for (i = 0; i < hashtable->nbuckets; i++) {
for (tuple = hashtable->buckets[i]; tuple != NULL; tuple = tuple->next)
HeapTupleHeaderClearMatch(HJTUPLE_MINTUPLE(tuple));
}
/* ... and the same for the skew buckets, if any */
for (i = 0; i < hashtable->nSkewBuckets; i++) {
int j = hashtable->skewBucketNums[i];
HashSkewBucket* skewBucket = hashtable->skewBucket[j];
for (tuple = skewBucket->tuples; tuple != NULL; tuple = tuple->next)
HeapTupleHeaderClearMatch(HJTUPLE_MINTUPLE(tuple));
}
}
void ExecReScanHash(HashState* node)
{
/*
* if chgParam of subnode is not null then plan will be re-scanned by
* first ExecProcNode.
*/
if (node->ps.lefttree->chgParam == NULL)
ExecReScan(node->ps.lefttree);
}
/*
* ExecHashBuildSkewHash
*
* Set up for skew optimization if we can identify the most common values
* (MCVs) of the outer relation's join key. We make a skew hash bucket
* for the hash value of each MCV, up to the number of slots allowed
* based on available memory.
*/
static void ExecHashBuildSkewHash(HashJoinTable hashtable, Hash* node, int mcvsToUse)
{
HeapTupleData* statsTuple = NULL;
Datum* values = NULL;
int nvalues;
float4* numbers = NULL;
int nnumbers;
char stakind = STARELKIND_CLASS;
/* do nothing if we don't have room for at least one skew bucket */
/* Also, Do nothing if planner didn't identify the outer relation's join key */
if (mcvsToUse <= 0 || !OidIsValid(node->skewTable)) {
return;
}
if (isPartitionObject(node->skewTable, PART_OBJ_TYPE_TABLE_PARTITION, true)) {
stakind = STARELKIND_PARTITION;
}
/*
* Try to find the MCV statistics for the outer relation's join key.
*
* Note: We don't consider multi-column skew-optimization values here(improve later)
*/
statsTuple = SearchSysCache4(STATRELKINDATTINH,
ObjectIdGetDatum(node->skewTable),
CharGetDatum(stakind),
Int16GetDatum(node->skewColumn),
BoolGetDatum(node->skewInherit));
if (!HeapTupleIsValid(statsTuple)) {
return;
}
if (get_attstatsslot(statsTuple,
node->skewColType,
node->skewColTypmod,
STATISTIC_KIND_MCV,
InvalidOid,
NULL,
&values,
&nvalues,
&numbers,
&nnumbers)) {
double frac;
int nbuckets;
FmgrInfo* hashfunctions = NULL;
int i;
if (mcvsToUse > nvalues) {
mcvsToUse = nvalues;
}
/*
* Calculate the expected fraction of outer relation that will
* participate in the skew optimization. If this isn't at least
* SKEW_MIN_OUTER_FRACTION, don't use skew optimization.
*/
frac = 0;
for (i = 0; i < mcvsToUse; i++) {
frac += numbers[i];
}
if (frac < SKEW_MIN_OUTER_FRACTION) {
free_attstatsslot(node->skewColType, values, nvalues, numbers, nnumbers);
ReleaseSysCache(statsTuple);
return;
}
/*
* Okay, set up the skew hashtable.
*
* skewBucket[] is an open addressing hashtable with a power of 2 size
* that is greater than the number of MCV values. (This ensures there
* will be at least one null entry, so searches will always
* terminate.)
*
* Note: this code could fail if mcvsToUse exceeds INT_MAX/8 or
* MaxAllocSize/sizeof(void *)/8, but that is not currently possible
* since we limit pg_statistic entries to much less than that.
*/
nbuckets = 2;
while (nbuckets <= mcvsToUse) {
nbuckets <<= 1;
}
/* use two more bits just to help avoid collisions */
nbuckets <<= 2;
hashtable->skewEnabled = true;
hashtable->skewBucketLen = nbuckets;
/*
* We allocate the bucket memory in the hashtable's batch context. It
* is only needed during the first batch, and this ensures it will be
* automatically removed once the first batch is done.
*/
hashtable->skewBucket =
(HashSkewBucket**)MemoryContextAllocZero(hashtable->batchCxt, nbuckets * sizeof(HashSkewBucket*));
hashtable->skewBucketNums = (int*)MemoryContextAllocZero(hashtable->batchCxt, mcvsToUse * sizeof(int));
hashtable->spaceUsed += nbuckets * sizeof(HashSkewBucket*) + mcvsToUse * sizeof(int);
hashtable->spaceUsedSkew += nbuckets * sizeof(HashSkewBucket*) + mcvsToUse * sizeof(int);
if (hashtable->spaceUsed > hashtable->spacePeak) {
hashtable->spacePeak = hashtable->spaceUsed;
}
/*
* Create a skew bucket for each MCV hash value.
*
* Note: it is very important that we create the buckets in order of
* decreasing MCV frequency. If we have to remove some buckets, they
* must be removed in reverse order of creation (see notes in
* ExecHashRemoveNextSkewBucket) and we want the least common MCVs to
* be removed first.
*/
hashfunctions = hashtable->outer_hashfunctions;
for (i = 0; i < mcvsToUse; i++) {
uint32 hashvalue;
int bucket;
hashvalue = DatumGetUInt32(FunctionCall1(&hashfunctions[0], values[i]));
/*
* While we have not hit a hole in the hashtable and have not hit
* the desired bucket, we have collided with some previous hash
* value, so try the next bucket location. NB: this code must
* match ExecHashGetSkewBucket.
*/
bucket = hashvalue & (nbuckets - 1);
while (hashtable->skewBucket[bucket] != NULL && hashtable->skewBucket[bucket]->hashvalue != hashvalue) {
bucket = (bucket + 1) & (nbuckets - 1);
}
/*
* If we found an existing bucket with the same hashvalue, leave
* it alone. It's okay for two MCVs to share a hashvalue.
*/
if (hashtable->skewBucket[bucket] != NULL) {
continue;
}
/* Okay, create a new skew bucket for this hashvalue. */
hashtable->skewBucket[bucket] =
(HashSkewBucket*)MemoryContextAlloc(hashtable->batchCxt, sizeof(HashSkewBucket));
hashtable->skewBucket[bucket]->hashvalue = hashvalue;
hashtable->skewBucket[bucket]->tuples = NULL;
hashtable->skewBucketNums[hashtable->nSkewBuckets] = bucket;
hashtable->nSkewBuckets++;
hashtable->spaceUsed += SKEW_BUCKET_OVERHEAD;
hashtable->spaceUsedSkew += SKEW_BUCKET_OVERHEAD;
if (hashtable->spaceUsed > hashtable->spacePeak) {
hashtable->spacePeak = hashtable->spaceUsed;
}
}
free_attstatsslot(node->skewColType, values, nvalues, numbers, nnumbers);
}
ReleaseSysCache(statsTuple);
}
/*
* ExecHashGetSkewBucket
*
* Returns the index of the skew bucket for this hashvalue,
* or INVALID_SKEW_BUCKET_NO if the hashvalue is not
* associated with any active skew bucket.
*/
int ExecHashGetSkewBucket(HashJoinTable hashtable, uint32 hashvalue)
{
int bucket;
/*
* Always return INVALID_SKEW_BUCKET_NO if not doing skew optimization (in
* particular, this happens after the initial batch is done).
*/
if (!hashtable->skewEnabled)
return INVALID_SKEW_BUCKET_NO;
/*
* Since skewBucketLen is a power of 2, we can do a modulo by ANDing.
*/
bucket = hashvalue & (hashtable->skewBucketLen - 1);
/*
* While we have not hit a hole in the hashtable and have not hit the
* desired bucket, we have collided with some other hash value, so try the
* next bucket location.
*/
while (hashtable->skewBucket[bucket] != NULL && hashtable->skewBucket[bucket]->hashvalue != hashvalue)
bucket = (bucket + 1) & (hashtable->skewBucketLen - 1);
/*
* Found the desired bucket?
*/
if (hashtable->skewBucket[bucket] != NULL)
return bucket;
/*
* There must not be any hashtable entry for this hash value.
*/
return INVALID_SKEW_BUCKET_NO;
}
/*
* ExecHashSkewTableInsert
*
* Insert a tuple into the skew hashtable.
*
* This should generally match up with the current-batch case in
* ExecHashTableInsert.
*/
static void ExecHashSkewTableInsert(HashJoinTable hashtable, TupleTableSlot* slot, uint32 hashvalue, int bucketNumber)
{
MinimalTuple tuple = ExecFetchSlotMinimalTuple(slot);
HashJoinTuple hashTuple;
int hashTupleSize;
errno_t rc = EOK;
/* Create the HashJoinTuple */
hashTupleSize = HJTUPLE_OVERHEAD + tuple->t_len;
hashTuple = (HashJoinTuple)MemoryContextAlloc(hashtable->batchCxt, hashTupleSize);
hashTuple->hashvalue = hashvalue;
rc = memcpy_s(HJTUPLE_MINTUPLE(hashTuple), tuple->t_len, tuple, tuple->t_len);
securec_check(rc, "\0", "\0");
HeapTupleHeaderClearMatch(HJTUPLE_MINTUPLE(hashTuple));
/* Push it onto the front of the skew bucket's list */
hashTuple->next = hashtable->skewBucket[bucketNumber]->tuples;
hashtable->skewBucket[bucketNumber]->tuples = hashTuple;
/* Account for space used, and back off if we've used too much */
hashtable->spaceUsed += hashTupleSize;
hashtable->spaceUsedSkew += hashTupleSize;
if (hashtable->spaceUsed > hashtable->spacePeak)
hashtable->spacePeak = hashtable->spaceUsed;
while (hashtable->spaceUsedSkew > hashtable->spaceAllowedSkew)
ExecHashRemoveNextSkewBucket(hashtable);
/* Check we are not over the total spaceAllowed, either */
if (hashtable->spaceUsed > hashtable->spaceAllowed)
ExecHashIncreaseNumBatches(hashtable);
}
/*
* ExecHashRemoveNextSkewBucket
*
* Remove the least valuable skew bucket by pushing its tuples into
* the main hash table.
*/
static void ExecHashRemoveNextSkewBucket(HashJoinTable hashtable)
{
int bucketToRemove;
HashSkewBucket* bucket = NULL;
uint32 hashvalue;
int bucketno;
int batchno;
HashJoinTuple hashTuple;
/* Locate the bucket to remove */
bucketToRemove = hashtable->skewBucketNums[hashtable->nSkewBuckets - 1];
bucket = hashtable->skewBucket[bucketToRemove];
/*
* Calculate which bucket and batch the tuples belong to in the main
* hashtable. They all have the same hash value, so it's the same for all
* of them. Also note that it's not possible for nbatch to increase while
* we are processing the tuples.
*/
hashvalue = bucket->hashvalue;
ExecHashGetBucketAndBatch(hashtable, hashvalue, &bucketno, &batchno);
/* Process all tuples in the bucket */
hashTuple = bucket->tuples;
while (hashTuple != NULL) {
HashJoinTuple nextHashTuple = hashTuple->next;
MinimalTuple tuple;
Size tupleSize;
/*
* This code must agree with ExecHashTableInsert. We do not use
* ExecHashTableInsert directly as ExecHashTableInsert expects a
* TupleTableSlot while we already have HashJoinTuples.
*/
tuple = HJTUPLE_MINTUPLE(hashTuple);
tupleSize = HJTUPLE_OVERHEAD + tuple->t_len;
/* Decide whether to put the tuple in the hash table or a temp file */
if (batchno == hashtable->curbatch) {
/* Move the tuple to the main hash table */
hashTuple->next = hashtable->buckets[bucketno];
hashtable->buckets[bucketno] = hashTuple;
/* We have reduced skew space, but overall space doesn't change */
hashtable->spaceUsedSkew -= tupleSize;
} else {
/* Put the tuple into a temp file for later batches */
Assert(batchno > hashtable->curbatch);
ExecHashJoinSaveTuple(tuple, hashvalue, &hashtable->innerBatchFile[batchno]);
pfree_ext(hashTuple);
hashtable->spaceUsed -= tupleSize;
hashtable->spaceUsedSkew -= tupleSize;
}
hashTuple = nextHashTuple;
/* allow this loop to be cancellable */
CHECK_FOR_INTERRUPTS();
}
/*
* Free the bucket struct itself and reset the hashtable entry to NULL.
*
* NOTE: this is not nearly as simple as it looks on the surface, because
* of the possibility of collisions in the hashtable. Suppose that hash
* values A and B collide at a particular hashtable entry, and that A was
* entered first so B gets shifted to a different table entry. If we were
* to remove A first then ExecHashGetSkewBucket would mistakenly start
* reporting that B is not in the hashtable, because it would hit the NULL
* before finding B. However, we always remove entries in the reverse
* order of creation, so this failure cannot happen.
*/
hashtable->skewBucket[bucketToRemove] = NULL;
hashtable->nSkewBuckets--;
pfree_ext(bucket);
hashtable->spaceUsed -= SKEW_BUCKET_OVERHEAD;
hashtable->spaceUsedSkew -= SKEW_BUCKET_OVERHEAD;
/*
* If we have removed all skew buckets then give up on skew optimization.
* Release the arrays since they aren't useful any more.
*/
if (hashtable->nSkewBuckets == 0) {
hashtable->skewEnabled = false;
pfree_ext(hashtable->skewBucket);
pfree_ext(hashtable->skewBucketNums);
hashtable->skewBucket = NULL;
hashtable->skewBucketNums = NULL;
hashtable->spaceUsed -= hashtable->spaceUsedSkew;
hashtable->spaceUsedSkew = 0;
}
}
/*
* ExecHashIncreaseBuckets
*
* Increase the original number of buckets during memory
* auto spread to avoid hash bucket conflict
*/
static void ExecHashIncreaseBuckets(HashJoinTable hashtable)
{
int64 ntotal = 0;
int64 nmove = 0;
errno_t rc;
/* do nothing if we've decided to shut off growth */
if (!hashtable->growEnabled)
return;
/* do nothing if disk spill is already happened */
if (hashtable->nbatch > 1)
return;
/* do nothing if there's still enough space */
if (hashtable->totalTuples * 2 <= hashtable->nbuckets)
return;
/* safety check to avoid overflow */
if ((uint32)hashtable->nbuckets > Min(INT_MAX, MaxAllocSize / (sizeof(HashJoinTuple))) / 2)
return;
hashtable->buckets = (HashJoinTuple*)repalloc(hashtable->buckets, hashtable->nbuckets * 2 * sizeof(HashJoinTuple));
rc = memset_s(hashtable->buckets + hashtable->nbuckets,
hashtable->nbuckets * sizeof(HashJoinTuple),
0,
hashtable->nbuckets * sizeof(HashJoinTuple));
securec_check(rc, "\0", "\0");
/*
* Scan through the existing hash table entries and dump out any that are
* no longer of the current batch.
*/
for (int i = 0; i < hashtable->nbuckets; i++) {
HashJoinTuple htuple = hashtable->buckets[i];
HashJoinTuple prev = NULL;
HashJoinTuple next = NULL;
while (htuple != NULL) {
int offset = (htuple->hashvalue >> hashtable->log2_nbuckets) & 1;
ntotal++;
next = htuple->next;
if (offset == 1) {
if (prev == NULL)
hashtable->buckets[i] = htuple->next;
else
prev->next = htuple->next;
htuple->next = hashtable->buckets[i + hashtable->nbuckets];
hashtable->buckets[i + hashtable->nbuckets] = htuple;
Assert((int32)(htuple->hashvalue % (hashtable->nbuckets * 2)) == i + hashtable->nbuckets);
nmove++;
} else {
prev = htuple;
Assert((int32)(htuple->hashvalue % (hashtable->nbuckets * 2)) == i);
}
htuple = next;
}
/* allow this loop to be cancellable */
CHECK_FOR_INTERRUPTS();
}
/*
* If we dumped out either all or none of the tuples in the table, disable
* further expansion of nbatch. This situation implies that we have
* enough tuples of identical hashvalues to overflow spaceAllowed.
* Increasing nbatch will not fix it since there's no way to subdivide the
* group any more finely. We have to just gut it out and hope the server
* has enough RAM.
*/
if (nmove == 0 || nmove == ntotal) {
hashtable->growEnabled = false;
#ifdef HJDEBUG
printf("Disabling further increase of nbatch or nbucket\n");
#endif
}
hashtable->nbuckets = hashtable->nbuckets * 2;
hashtable->log2_nbuckets++;
}
void ExecHashTableStats(HashJoinTable hashtable, int planid)
{
int fillRows = 0;
int singleNum = 0;
int doubleNum = 0;
int conflictNum = 0;
int chainLen = 0;
int maxChainLen = 0;
for (int i = 0; i < hashtable->nbuckets; i++) {
HashJoinTuple htuple = hashtable->buckets[i];
/* record each hash chain's length and accumulate hash element */
chainLen = 0;
while (htuple != NULL) {
fillRows++;
chainLen++;
htuple = htuple->next;
}
/* record the number of hash chains with length equal to 1 */
if (chainLen == 1)
singleNum++;
/* record the number of hash chains with length equal to 2 */
if (chainLen == 2)
doubleNum++;
/* mark if the length of hash chain is greater than 3, we meet hash confilct */
if (chainLen >= 3)
conflictNum++;
/* record the length of the max hash chain */
if (chainLen > maxChainLen)
maxChainLen = chainLen;
}
/* print the information */
ereport(LOG,
(errmodule(MOD_VEC_EXECUTOR),
errmsg("[HashJoin(%d) batch %d] Hash Table Profiling: table size: %d,"
" hash elements: %d, table fill ratio %.2f, max hash chain len: %d,"
" %d chains have length 1, %d chains have length 2, %d chains have conficts "
"with length >= 3.",
planid,
hashtable->curbatch,
hashtable->nbuckets,
fillRows,
(double)fillRows / hashtable->nbuckets,
maxChainLen,
singleNum,
doubleNum,
conflictNum)));
}
/*
* Allocate 'size' bytes from the currently active HashMemoryChunk
*/
static void* dense_alloc(HashJoinTable hashtable, Size size)
{
HashMemoryChunk newChunk;
char* ptr = NULL;
/* just in case the size is not already aligned properly */
size = MAXALIGN(size);
/*
* If tuple size is larger than of 1/4 of chunk size, allocate a separate
* chunk.
*/
if (size > HASH_CHUNK_THRESHOLD) {
/* allocate new chunk and put it at the beginning of the list */
newChunk = (HashMemoryChunk)MemoryContextAlloc(hashtable->batchCxt, offsetof(HashMemoryChunkData, data) + size);
newChunk->maxlen = size;
newChunk->used = 0;
newChunk->ntuples = 0;
/*
* Add this chunk to the list after the first existing chunk, so that
* we don't lose the remaining space in the "current" chunk.
*/
if (hashtable->chunks != NULL) {
newChunk->next = hashtable->chunks->next;
hashtable->chunks->next = newChunk;
} else {
newChunk->next = hashtable->chunks;
hashtable->chunks = newChunk;
}
newChunk->used += size;
newChunk->ntuples += 1;
return newChunk->data;
}
/*
* See if we have enough space for it in the current chunk (if any).
* If not, allocate a fresh chunk.
*/
if ((hashtable->chunks == NULL) || (hashtable->chunks->maxlen - hashtable->chunks->used) < size) {
/* allocate new chunk and put it at the beginning of the list */
newChunk = (HashMemoryChunk)MemoryContextAlloc(
hashtable->batchCxt, offsetof(HashMemoryChunkData, data) + HASH_CHUNK_SIZE);
newChunk->maxlen = HASH_CHUNK_SIZE;
newChunk->used = size;
newChunk->ntuples = 1;
newChunk->next = hashtable->chunks;
hashtable->chunks = newChunk;
return newChunk->data;
}
/* There is enough space in the current chunk, let's add the tuple */
ptr = hashtable->chunks->data + hashtable->chunks->used;
hashtable->chunks->used += size;
hashtable->chunks->ntuples += 1;
/* return pointer to the start of the tuple memory */
return ptr;
}
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