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MDEV-6111 Optimizer Trace

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This task involves the implementation for the optimizer trace.

This feature produces a trace for any SELECT/UPDATE/DELETE/,
which contains information about decisions taken by the optimizer during
the optimization phase (choice of table access method, various costs,
transformations, etc). This feature would help to tell why some decisions were
taken by the optimizer and why some were rejected.

Trace is session-local, controlled by the @@optimizer_trace variable.
To enable optimizer trace we need to write:
   set @@optimizer_trace variable= 'enabled=on';

To display the trace one can run:
   SELECT trace FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;

This task also involves:
    MDEV-18489: Limit the memory used by the optimizer trace
    introduces a switch optimizer_trace_max_mem_size which limits
    the memory used by the optimizer trace. This was implemented by
    Sergei Petrunia.
This commit is contained in:
Varun Gupta
2019-02-13 11:22:16 +05:30
parent 6b979416e0
commit be8709eb7b
47 changed files with 8227 additions and 622 deletions
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15
sql/sql_class.h
View File

@ -28,6 +28,7 @@
#include "rpl_tblmap.h"
#include "mdl.h"
#include "field.h" // Create_field
#include "opt_trace_context.h"
#include "probes_mysql.h"
#include "sql_locale.h" /* my_locale_st */
#include "sql_profile.h" /* PROFILING */
@ -569,6 +570,8 @@ typedef struct system_variables
ulonglong long_query_time;
ulonglong max_statement_time;
ulonglong optimizer_switch;
ulonglong optimizer_trace;
ulong optimizer_trace_max_mem_size;
sql_mode_t sql_mode; ///< which non-standard SQL behaviour should be enabled
sql_mode_t old_behavior; ///< which old SQL behaviour should be enabled
ulonglong option_bits; ///< OPTION_xxx constants, e.g. OPTION_PROFILING
@ -1350,6 +1353,14 @@ public:
restore_security_context(THD *thd, Security_context *backup);
#endif
bool user_matches(Security_context *);
/**
Check global access
@param want_access The required privileges
@param match_any if the security context must match all or any of the req.
* privileges.
@return True if the security context fulfills the access requirements.
*/
bool check_access(ulong want_access, bool match_any = false);
};
@ -2306,6 +2317,8 @@ public:
Security_context main_security_ctx;
Security_context *security_ctx;
Security_context *security_context() const { return security_ctx; }
void set_security_context(Security_context *sctx) { security_ctx = sctx; }
/*
Points to info-string that we show in SHOW PROCESSLIST
@ -2989,6 +3002,7 @@ public:
ulonglong bytes_sent_old;
ulonglong affected_rows; /* Number of changed rows */
Opt_trace_context opt_trace;
pthread_t real_id; /* For debugging */
my_thread_id thread_id, thread_dbug_id;
uint32 os_thread_id;
@ -3297,6 +3311,7 @@ public:
void reset_for_reuse();
bool store_globals();
void reset_globals();
bool trace_started();
#ifdef SIGNAL_WITH_VIO_CLOSE
inline void set_active_vio(Vio* vio)
{