For #4674
This is a udaf for approximate topn using Space-Saving algorithm. At present, we can only calculate
the frequent items and their frequencies in a certain column, based on which we can implement similar
topN functions supported by Kylin in the future.
I have also added a test to calculate the accuracy of this algorithm. The following is a rough running result.
The total amount of data is 1 million lines and follows the Zipfian distribution, where Element Cardinality
represents the data cardinality, 20X, 50X.. The value representing space_expand_rate is 20,50, which is
used to set the counter number in the space-saving algorithm
```
zf exponent = 0.5
Element cardinality 20X 50X 100X
1000 100% 100% 100%
10000 100% 100% 100%
100000 100% 100% 100%
500000 94% 98% 99%
zf exponent = 0.6，1
Element cardinality 20X 50X 100X
1000 100% 100% 100%
10000 100% 100% 100%
100000 100% 100% 100%
500000 100% 100% 100%
```
BE can not graceful exit because some threads are running in endless
loop. This patch do the following optimization:
- Use the well encapsulated Thread and ThreadPool instead of std::thread
and std::vector<std::thread>
- Use CountDownLatch in thread's loop condition to avoid endless loop
- Introduce a new class Daemon for daemon works, like tcmalloc_gc,
memory_maintenance and calculate_metrics
- Decouple statistics type TaskWorkerPool and StorageEngine notification
by submit tasks to TaskWorkerPool's queue
- Reorder objects' stop and deconstruct in main(), i.e. stop network
services at first, then internal services
- Use libevent in pthreads mode, by calling evthread_use_pthreads(),
then EvHttpServer can exit gracefully in multi-threads
- Call brpc::Server's Stop() and ClearServices() explicitly
Sometimes we want to detect the hotspot of a cluster, for example, hot scanned tablet, hot wrote tablet,
but we have no insight about tablets in the cluster.
This patch introduce tablet level metrics to help to achieve this object, now support 4 metrics on tablets: `query_scan_bytes `, `query_scan_rows `, `flush_bytes `, `flush_count `.
However, one BE may holds hundreds of thousands of tablets, so I add a parameter for the metrics HTTP request,
and not return tablet level metrics by default.
Redesign metrics to 3 layers:
MetricRegistry - MetricEntity - Metrics
MetricRegistry : the register center
MetricEntity : the entity registered on MetricRegistry. Generally a MetricRegistry can be registered on several
MetricEntities, each of MetricEntity is an independent entity, such as server, disk_devices, data_directories, thrift
clients and servers, and so on.
Metric : metrics of an entity. Such as fragment_requests_total on server entity, disk_bytes_read on a disk_device entity,
thrift_opened_clients on a thrift_client entity.
MetricPrototype: the type of a metric. MetricPrototype is a global variable, can be shared by the same metrics across
different MetricEntities.
Fix: #3946
CL:
1. Add prepare phase for `from_unixtime()`, `date_format()` and `convert_tz()` functions, to handle the format string once for all.
2. Find the cctz timezone when init `runtime state`, so that don't need to find timezone for each rows.
3. Add constant rewrite rule for `utc_timestamp()`
4. Add doc for `to_date()`
5. Comment out the `push_handler_test`, it can not run in DEBUG mode, will be fixed later.
6. Remove `timezone_db.h/cpp` and add `timezone_utils.h/cpp`
The performance shows bellow:
11,000,000 rows
SQL1: `select count(from_unixtime(k1)) from tbl1;`
Before: 8.85s
After: 2.85s
SQL2: `select count(from_unixtime(k1, '%Y-%m-%d %H:%i:%s')) from tbl1 limit 1;`
Before: 10.73s
After: 4.85s
The date string format seems still slow, we may need a further enhancement about it.
Support Grouping Sets, Rollup and Cube to extend group by statement
support GROUPING SETS syntax
```
SELECT a, b, SUM( c ) FROM tab1 GROUP BY GROUPING SETS ( (a, b), (a), (b), ( ) );
```
cube or rollup like
```
SELECT a, b,c, SUM( d ) FROM tab1 GROUP BY ROLLUP|CUBE(a,b,c)
```
[ADD] support grouping functions in expr like grouping(a) + grouping(b) (#2039)
[FIX] fix analyzer error in window function(#2039)
This CL changes:
1. add function bitmap_to_string and bitmap_from_string, which will
convert a bitmap to/from string which contains all bit in bitmap
2. add function murmur_hash3_32, which will compute murmur hash for
input strings
3. make the function cast float to string the same with user result
logic
I add ChunkAllocator in this CL to put unused memory chunk to a chunk
pool other than return it to system allocator. Now we only change
MemPool's chunk allocation and free to this.
And two configuration are introduduced too. 'chunk_reserved_bytes_limit'
is the limit of how many bytes this chunk pool can reserve in total and
its default value is 2147483648(2GB). 'use_mmap_allocate_chunk': if
chunk is allocated via mmap and default value is false.
And in my test case with default configuration a simple like
"select * from table limit 10", this can improve throughput from 280 QPS
to to 650 QPS. And when I config 'chunk_reserved_bytes_limit' to 0,
which means this is disabled, the throughput is the same with origin's.
1. max io util of disks
2. max network send/receive bytes rate of all network devices
3. base/cumulative compaction request counter and failure counter
* Add UserFunctionCache to cache UDF's library
This patch replace LibCache with UserFunctionCache. LibCache use HDFS
URL to identify a UDF's Library, and when BE process restart all of
downloaded library should be loaded another time. We use function id
corresponding to a library, and when process restart, all downloaded
libraries can be loaded without another downloading.
* update
* Reduce UT binary size
Almost every module depend on ExecEnv, and ExecEnv contains all
singleton, which make UT binary contains all object files.
This patch seperate ExecEnv's initial and destory to anthor file to
avoid other file's dependence. And status.cc include debug_util.h which
depend tuple.h tuple_row.h, and I move get_stack_trace() to
stack_util.cpp to reduce status.cc's dependence.
I add USE_RTTI=1 to build rocksdb to avoid linking librocksdb.a
Issue: #292
* Update
