In qc_sqlite the fields that a particular function refers to are now
collected and reported. Qc_mysqlembedded needs to be updated accordingly
and also the compare utility. For subsequent commits.
With sqlite3 3110100, which is used in MaxScale, the the generation
of the used op-codes could sometime generate code that did not define
all opcodes. That resulted then in a compilation error like:
.../sqlite-bld-3110100/sqlite3.c: In function 'sqlite3VdbeExec':
.../sqlite-bld-3110100/sqlite3.c:75427:6: error: 'OP_Real' undeclared
(first use in this function)
case OP_Real: { /* same as TK_FLOAT, out2 */
^
The reason seems to be that if a particular op-code was not used, the
generation stopped at that point:
#define OP_Explain 160
#define OP_NotUsed_161 161
With mkopcodeh.tcl from sqlite3 version 3200000, the generated code
looks like
#define OP_NotUsed_161 161
#define OP_Real 162 /* same as TK_FLOAT,
synopsis: r[P2]=P4 */
and the code compiles.
Thus, mkopcodeh.tsl is updated from the newer sqlite3 version.
In case of very large compound selects or an INSERT with many
values, qc_sqlite could run out of stack space. To deal with
that, the critical recursion is turned into an iteration.
Alias handling must be made so that in a subselect, aliases created
in an outer select are available, but aliases created in another
subselect are not.
The sqlite3 initialization is done a bit more properly now.
It is also ensured that issues are logged at most once, even
if a statement is parsed twice.
All callbacks called by sqlite now only access the thread specific
QcSqliteInfo and call the corresponding function on that instance.
This is the first step in making qc_sqlite exception safe from the
point of view of sqlite3.
As the diff is confusing, basically the ONLY thing that has been
done is:
BEFORE:
-------
class QcSqliteInfo
{
...
};
static void some_helper(...) { ... }
void mxs_someCallback(...)
{
QC_TRACE();
QcSqliteInfo* info = this_thread.pInfo;
ss_dassert(info);
info->m_status = ...;
some_helper(info, ...);
}
AFTER:
------
class QcSqliteInfo
{
...
void some_helper(...) { ... }
void mxs_someCallback(...)
{
m_status = ...;
some_helper(this, ...);
}
};
void mxs_someCallback(...)
{
QC_TRACE();
QcSqliteInfo* pInfo = this_thread.pInfo;
ss_dassert(pInfo);
pInfo->mxs_someCallback(...);
}
With this change, for a statement like
SELECT t2.a FROM t1 t2;
the affected field is reported as t1.a and not as t2.a, as it
was before.
For a statement like
SELECT t.f FROM d.t;
qc_mysqlembedded will now return "d.t.f" as the affected field,
while qc_sqlite will still return "t.f" as both implementations did
before. In qc_mysqlembedded's case that is a side-effect of the
alias handling. To get qc_sqlite to return the same (which would
be good), the table names would have to be collected in a smarter
way than they are now.
Alias names for tables are now collected, so that the true
table name of a referred to field can be reported. That modification
will be made in a subsequent commit.
If a particular table appears in a statement multiple times,
qc_get_table_names will report it as many times as it appears.
Each name should be reported just once. Same applies for
database names.
The update_names() will have to be updated to take a possible alias
name as well. That needs to be tracked inside QcSqliteInfo, so that
when there is a statement like "select t2.a from t1 t2" we report
the field as t1.a and not as t2.a.
The structure for storing statement information is now a C++ class.
At least initially it will not be turned into a full-fledged class
that would contain all functionality, but the code will be a mishmash
of C and C++.
- Fields in CTEs are marked as being used in subselects.
- In qc_mysqlembedded all selects must be walked if CTE is present.
- In qc_sqlite unions need special handling.
The default sql mode must now be provided explicitly when the query
classifier is setup. This is in preparation for "sql_mode" becoming
a global configuration parameter of MaxScale.
The sql mode is now a property of the info object used for storing
parsing related information. It is initialized with the value of the
sql mode qc_sqlite was initialized with.
This will be further changed so that the mode can be adjusted at
runtime so that the sql mode can be the property of a session. That
is, once set it will affect all future parsing for that session.
