Query

instr_unique_sql_count

Parameter description: Specifies the maximum number of unique SQL records to be collected. The value 0 indicates that the function of collecting unique SQL information is disabled.

If the value is changed from a larger one to a smaller one, unique SQL statistics will be reset and re-collected (the standby node does not support this function). There is no impact if the value is changed from a smaller one to a larger one.

When the number of unique SQL records generated in the system (to view the statistics, query dbe_perf.statement or dbe_perf.summary_statement) is greater than the value of instr_unique_sql_count, the extra unique SQL records are not collected.

In the x86-based centralized deployment scenario, the hardware configuration specifications are 32-core CPU/256 GB memory. When the Benchmark SQL 5.0 tool is used to test performance, the performance fluctuates by about 3% by enabling or disabling this parameter.

This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Value range: an integer ranging from 0 to 2147483647

Default value: 200000

instr_unique_sql_track_type

Parameter description: Specifies which SQL statements are recorded in Unique SQL.

This parameter is a USERSET parameter. Set it based on instructions provided in Table 1.

Default value: top

unique_sql_retention_time

Parameter description: Specifies the interval for cleaning the unique SQL hash table. The default value is 30 minutes.

This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Value range: an integer ranging from 1 to 3650. The unit is minute.

Default value: 30min

enable_instr_rt_percentile

Parameter description: Specifies whether to enable the function of calculating the response time of 80% and 95% SQL statements in the system.

This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Value range: Boolean

• on indicates that the function of calculating the response time of 80% and 95% SQL statements is enabled.
• off indicates that the function of calculating the response time of 80% and 95% SQL statements is disabled.

Default value: on

percentile

Parameter description: Specifies the percentage of SQL statements whose response time is to be calculated by the background calculation thread.

This parameter is an INTERNAL parameter. Set it based on instructions provided in Table 1.

Value range: a string

Default value: "80,95"

instr_rt_percentile_interval

Parameter description: Specifies the interval at which the background calculation thread calculates the SQL response time.

This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Value range: an integer ranging from 0 to 3600. The unit is s.

Default value: 10s

enable_instr_cpu_timer

Parameter description: Specifies whether to capture the CPU time consumed during SQL statement execution.

In the x86-based centralized deployment scenario, the hardware configuration specifications are 32-core CPU/256 GB memory. When the Benchmark SQL 5.0 tool is used to test performance, the performance fluctuates by about 3.5% by enabling or disabling this parameter.

This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Value range: Boolean

• on indicates that the CPU time consumed during SQL statement execution is captured.
• off indicates that the CPU time consumed during SQL statement execution is not captured.

Default value: on

query_log_file (Discarded)

Parameter description: Specifies the name of a slow query log file on the server. If enable_slow_query_log is set to ON, slow query records are written into log files. Only the sysadmin user can access this parameter. Generally, log file names are generated in strftime mode. Therefore, the system time can be used to define log file names, which are implemented using the escape character %. This function has been discarded in this version.

This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1.

You are advised to use escape character % to specify the log file names for efficient management of log files.

Value range: a string

Default value: slow_query_log-%Y-%m-%d_%H%M%S.log

query_log_directory (Discarded)

Parameter description: Specifies the directory for storing low query log files when enable_slow_query_log is set to on. Only the sysadmin user can access this parameter. It can be an absolute path or a relative path (relative to the data directory), which has been discarded in this version.

This parameter is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

If this parameter is set to an invalid path, the cluster cannot be started.

Valid path: You have read and write permissions on the path.

Invalid path: You do not have read or write permission on the path.

Value range: a string

Default value: specified during installation

asp_log_directory

Parameter description: Specifies the directory for storing ASP log files on the server when asp_flush_mode is set to all or file. The value can be an absolute path, or relative to the data directory. Only the sysadmin user can access this parameter.

This parameter is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

If this parameter is set to an invalid path, the cluster cannot be started.

• Valid path: You have read and write permissions on the path.
• Invalid path: You do not have read or write permissions on an invalid path.

Value range: a string

Default value: specified during installation

perf_directory

Parameter description: Specifies the directory of the output file of the performance view dotting task. Only the sysadmin user can access this parameter. The value can be an absolute path, or relative to the data directory.

This parameter is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

• Valid path: You have read and write permissions on the path.
• Invalid path: You do not have read or write permissions on an invalid path.

Value range: a string

Default value: specified during installation

enable_stmt_track

Parameter description: Specifies whether to enable the full/slow SQL statement feature.

In the x86-based centralized deployment scenario, the hardware configuration specifications are 32-core CPU/256 GB memory. When the Benchmark SQL 5.0 tool is used to test performance, the performance fluctuates by about 1.2% by enabling or disabling this parameter.

This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Value range: Boolean

• on: Full/Slow SQL capture is enabled.
• off: Full/Slow SQL capture is disabled.

Default value: on

track_stmt_parameter

Parameter description: After track_stmt_parameter is enabled, the executed statements recorded in statement_history are not normalized. The complete SQL statement information can be displayed to help the database administrator locate faults. For a simple query, the complete statement information is displayed. For a PBE statement, the complete statement information and information about each variable value are displayed. The format is "query string; parameters:$1=value1,$2=value2, ...". This parameter is used to display full SQL information for users and is not controlled by the track_activity_query_size parameter. When the SQL bypass logic is used for PBE statements, parameters are directly delivered to DNs. Therefore, the number of complete statements cannot be obtained by querying statement_history on CNs. In addition, DNs do not have query character strings. Therefore, complete statement information cannot be obtained by querying statement_history on DNs.

This is a SIGHUP parameter. Set it based on instructions provided in Table 2.

Value range: Boolean

• on: The function of displaying complete SQL statement information is enabled.
• off: The function of displaying complete SQL statement information is disabled.

Default value: off

track_stmt_session_slot

Parameter description: Specifies the maximum number of full/slow SQL statements that can be cached in a session. If the number of full/slow SQL statements exceeds this value, new statements will not be traced until the flush thread flushes the cached statements to the disk to reserve free space.

This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Value range: an integer ranging from 0 to 2147483647

Default value: 1000

track_stmt_details_size

Parameter description: Specifies the maximum size of execution events that can be collected by a single statement.

This parameter is a USERSET parameter. Set it based on instructions provided in Table 1.

Value range: an integer ranging from 0 to 100000000. The unit is byte.

Default value: 4096

track_stmt_retention_time

Parameter description: Specifies the retention period of full/slow SQL statement records. This parameter is a combination of parameters. This parameter is read every 60 seconds and records older than the retention period are deleted. Only the sysadmin user can access this parameter.

This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Value range: a string consisting of two parts in the format of 'full sql retention time, slow sql retention time'.

• full sql retention time indicates the retention period of full SQL statements. The value ranges from 0 to 86400. The unit is second.
• slow sql retention time indicates the retention period of slow SQL statements. The value ranges from 0 to 604800. The unit is second.

Default value: 3600,604800

track_stmt_stat_level

Parameter description: Determines the level of statement execution tracing.

This parameter is a USERSET parameter. Set it based on instructions provided in Table 1. Letters are case insensitive. If the full SQL function is enabled, the performance will be affected and a large amount of disk space may be occupied.

Value range: a string

This parameter consists of two parts in the format of 'full sql stat level, slow sql stat level'.

• The first part indicates the tracing level of full SQL statements. The value can be OFF, L0, L1, or L2.
• The second part indicates the tracing level of slow SQL statements. The value can be OFF, L0, L1, or L2.
  

  If the tracing level of full SQL statements is not OFF, the current SQL statement tracing level is a higher level (L2 > L1 > L0) of full and slow SQL statements. For details about the levels, see "System Catalogs and System Views > System Catalogs > STATEMENT_HISTORY > STATEMENT_HISTORY columns" in the Developer Guide.

Default value: OFF,L0

track_stmt_standby_chain_size

Parameter description: Specifies the maximum memory and disk space occupied by fast/slow SQL statement records on the standby node. This parameter is a combination of parameters. This parameter is unavailable in a distributed system.