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SHOW PLANCACHE
Shows all query statements that MemSQL has compiled and executed, as well as cumulative query execution statistics associated with each plan.
Syntax
SHOW PLANCACHE
Remarks
SHOW PLANCACHEis a MemSQL extension (it doesn’t exist in MySQL).- All counters shown by
SHOW PLANCACHEare cleared when MemSQL is restarted. - This command can be run on any MemSQL node (see Node Requirements for MemSQL Commands).
Output
| Column | Description |
|---|---|
Database |
Context database selected with USE <db_name> when query was compiled. |
QueryText |
Query text with all numeric and string parameters replaced by tags (depending on parameter and/or query type). @ is used for integers and ^ for string parameters. ? is always used for INSERT queries. |
PlanID |
ID of the plan. |
PlanType |
Plan type, interpreted or compiled. |
Commits |
Number of successful executions of the query. |
Rollbacks |
Number of unsuccessful executions of the query (i.e. if the query was aborted or it encountered runtime errors). |
RowCount |
Cumulative number of rows returned by a SELECT query or the cumulative number of rows inserted, updated, or deleted for an INSERT, UPDATE, or DELETE query. |
ExecutionTime |
Cumulative time (in milliseconds) spent executing the query. |
AverageExecTime |
Average plan execution time. |
LogBufferTime |
NULL for SELECT queries, otherwise the cumulative time (in milliseconds) spent waiting to reserve space in the transaction buffer for this query. A larger transaction buffer and faster disk can help reduce it. |
LogFlushTime |
NULL for SELECT queries, otherwise the cumulative time (in milliseconds) spent waiting until changes made by this query are flushed to disk. A faster disk can help reduce it. |
RowLockTime |
NULL for SELECT queries, otherwise the cumulative time (in milliseconds) spent waiting to acquire exclusive row locks. |
StreamedRows |
(Cluster Only) Cumulative number of rows streamed from leaves and processed by the SELECT query. |
LeafNetworkTime |
(Cluster Only) Cumulative time (in milliseconds) spent waiting for results from leaves. This includes the time spent executing queries on the leaves. |
QueuedTime |
Query queued time. |
LastExecuted |
Query last execution time. |
CpuTime |
The amount of CPU time, in milliseconds, spent executing the query. |
AverageMemoryUse |
The average amount of memory used to execute this query. Any temporary memory allocation needed to execute a query including those for hash tables, sorts, result tables, etc. is tracked here. |
PlanWarnings |
Any warnings associated with the plan. |
AverageMaxMemoryUse |
This is the maximum memory use of each run, averaged across all runs of the same query plan. |
The OptimizerNotes column may contain the following information:
-
table_row_counts: Table row counts and other statistics. -
prospective_histograms: Queries in the plancache that could have made use of histograms. -
is_single_partition: Value is true for a single partition; otherwise, false. -
average_leaf_memory,average_runtime: Average memory usage by leaf and average query runtime statistics collected by Workload Management. -
num_broadcasts,num_reshuffles: Number of broadcasts or reshuffles in the plan.InfoMemSQL returns
-1fornum_reshufflesandnum_broadcastswhen the workload manager is not managing (or tracking) the query based on the number of connections (or threads).For example:
--- "LogBufferTime": 0, "LogFlushTime": 0, "OptimizerNotes": "{\"num_broadcasts\": -1, \"num_reshuffles\": -1, \"is_single_partition\": false, \"average_leaf_memory\": 0, \"average_runtime\": 0}", "PlanId": 57080, "PlanType": "LLVM", "PlanWarnings": "", ---
Example
SHOW PLANCACHE;
****
+--------------------+----------------------------------+--------+----------+---------+-----------+----------+---------------+-----------------+---------------+--------------+-------------+--------------+-----------------+------------+---------------------+------------------+--------------+-------------------------------------------------------------------------------------------------------------------------+---------+---------------------+
| Database | QueryText | PlanId | PlanType | Commits | Rollbacks | RowCount | ExecutionTime | AverageExecTime | LogBufferTime | LogFlushTime | RowLockTime | StreamedRows | LeafNetworkTime | QueuedTime | LastExecuted | AverageMemoryUse | PlanWarnings | OptimizerNotes | CpuTime | AverageMaxMemoryUse |
+--------------------+----------------------------------+--------+----------+---------+-----------+----------+---------------+-----------------+---------------+--------------+-------------+--------------+-----------------+------------+---------------------+------------------+--------------+-------------------------------------------------------------------------------------------------------------------------+---------+---------------------+
| information_schema | SELECT @@memsql_id | 0 | LLVM | 4 | 0 | 4 | 347 | 86 | NULL | NULL | NULL | 0 | 0 | 0 | 2019-07-01 13:33:15 | 84237 | | {"num_broadcasts": 0, "num_reshuffles": 0, "is_single_partition": true, "average_leaf_memory": 0, "average_runtime": 0} | 9 | 131072 |
| information_schema | SELECT @@memsql_version | 1 | LLVM | 1 | 0 | 1 | 157 | 157 | NULL | NULL | NULL | 0 | 0 | 0 | 2019-07-01 13:33:15 | 130681 | | {"num_broadcasts": 0, "num_reshuffles": 0, "is_single_partition": true, "average_leaf_memory": 0, "average_runtime": 0} | 13 | 131072 |
| | select @@version_comment limit @ | 2 | LLVM | 1 | 0 | 1 | 558 | 558 | NULL | NULL | NULL | 0 | 0 | 0 | 2019-07-01 13:33:23 | 130987 | | {"num_broadcasts": 0, "num_reshuffles": 0, "is_single_partition": true, "average_leaf_memory": 0, "average_runtime": 0} | 9 | 131072 |
+--------------------+----------------------------------+--------+----------+---------+-----------+----------+---------------+-----------------+---------------+--------------+-------------+--------------+-----------------+------------+---------------------+------------------+--------------+-------------------------------------------------------------------------------------------------------------------------+---------+---------------------+
