How to find the number of times a query has been executed

The following query was given to me by an experienced colleague. It shows the number of times different variations of a particular query has been executed. The information is collected from V$SQL which samples the contents in the Library Cache, a part of the Shared Pool.

SELECT SQL_ID, COUNT(DISTINCT SQL_ID) NUM_SQL_IDS, COUNT(CHILD_NUMBER) ANT_CHILD, SUM(EXECUTIONS) 
FROM V$SQL
WHERE SQL_TEXT LIKE ' select count(*) TOTALS from   scott.emp%'
GROUP BY ROLLUP(SQL_ID)
;

Here is parts of the output:

SQL_ID	NUM_SQL_IDS	ANT_CHILD	SUM(EXECUTIONS)
01b71y5wmr2bx	1	1	0
081ha7tszas19	1	3	2
0bfn4yj267xy0	1	2	34
0dk42bqfz6fbr	1	3	6
g1vq03475hqgc	1	3	10
g3hky4g8vu108	1	3	9
--------- Abbreviated ---------
	274	549	1940

From the output we can see that there are a number of variations of the query being executed. The numbers are being rolled up nicely at the end, letting us know that there are 274 unique SQL_IDs, 549 different child cursors with a total of 1940 executions.

This information can certainly be useful during an effort to tune the library cache.

How to execute and capture an SQL statement in the SMB at the same time

An experienced co-worker showed me this neat trick to execute an SQL statement and capture its execution plan in the SQL Plan Management Base at the same time.

/* First, select the bind variables used in the SQL statement you're interested in, into the variable value_string.
Record them in a text file. You will be using them later
*/
SELECT DECODE (value_string, 'NULL,', ''''',', value_string)
  FROM (  SELECT DECODE (datatype_string,
                         'VARCHAR2(32)', '''' || value_string || ''',',
                         value_string || ',')
                    value_string
            FROM v$sql_bind_capture
           WHERE sql_id = '4d6sdzm63st1u' AND child_number = 1
        ORDER BY position);

/*
Get the SQL text including the bind usage (but not the bind variable values)
*/
SET SERVEROUTPUT ON

DECLARE
   l_sql      VARCHAR2 (32000);
   l_sql_id   VARCHAR2 (30) := '4d6sdzm63st1u';
BEGIN
   BEGIN
      SELECT sql_fulltext
        INTO l_sql
        FROM v$sql                                          
       WHERE sql_id = l_sql_id AND ROWNUM < 2;
   EXCEPTION
      WHEN NO_DATA_FOUND
      THEN
         SELECT sql_text
           INTO l_sql
           FROM dba_hist_sqltext
          WHERE sql_id = l_sql_id AND ROWNUM < 2;
   END;

   DBMS_OUTPUT.put_line (l_sql);

/* Capture the baseline for this statement */ 
   EXECUTE IMMEDIATE
      'alter session set optimizer_capture_sql_plan_baselines=true';

/* Send the SQL including the bind variable values to the database */
   EXECUTE IMMEDIATE l_sql
      USING 5022000,
            9834,
            9822,
            9,
            4,
            6;
/* Turn the capture off again */
   EXECUTE IMMEDIATE
      'alter session set optimizer_capture_sql_plan_baselines=false';
END;
/

Query to search for details about a specific SQL ID in the cursor cache

I have plenty of examples that Oracle 12cR1 selects poor execution plans over good ones.
This is a recent example from one of my databases. Notice that there are two different plans for the same SQL ID, one that seems to take long per exection, and a good plan that executes each statement very quickly:

SELECT TO_CHAR(LAST_ACTIVE_TIME, 'dd.mm.yyyy hh24:mi') "last active",
       SQL_ID,
       PLAN_HASH_VALUE,
       SQL_PLAN_BASELINE "BASELINE", 
       SQL_PROFILE,
       IS_RESOLVED_ADAPTIVE_PLAN,
       CHILD_NUMBER AS "Child Num",
       ELAPSED_TIME,
       EXECUTIONS,
       ROUND(ELAPSED_TIME/1000000) "duration (sec)"
       ,CASE WHEN EXECUTIONS > 0 THEN
        ROUND( (ELAPSED_TIME/EXECUTIONS)/1000000, 1)
        ELSE
            NULL
       END "sec per exe"
FROM V$SQL 
WHERE SQL_ID =('fczwz45f4d46q')
ORDER BY LAST_ACTIVE_TIME DESC;

Result:

Last active	SQL_ID	PLAN_HASH_VALUE	BASELINE	SQL_PROFILE	Child Num	ELAPSED_TIME	EXECUTIONS	duration (sec)	sec per exe
16.08.2017 10:57	fczwz45f4d46q	2259800413		SYS_SQLPROF_0156739adc130001	0	350642099493	311	350642	1127,5
16.08.2017 01:39	fczwz45f4d46q	927328071		SYS_SQLPROF_0156739adc130001	9	2675614671	26048	2676	0,1

In this case, my goal is to create a fixed baseline for the execution plan with hash value 927328071.

How to find the plan for a particular SQL in the SMB

SELECT sql_text,plan_name,sql_handle,creator,origin,created, last_executed,enabled,accepted,fixed,autopurge,module
FROM   DBA_SQL_PLAN_BASELINES
WHERE  sql_text LIKE '%your sql text%';

Joined with v$sql, to reveal the SQL ID, and with some formatting: find all plans created for a specific SQL ID, including those no longer in the cursor cache:

select  b.SQL_handle,
        b.plan_name,
        b.origin,
        to_char(b.created, 'dd.mm.rrrr hh24:mi') created,
        to_char(b.last_modified, 'dd.mm.rrrr hh24:mi')last_mod, 
        to_char(b.last_executed, 'dd.mm.rrrr hh24:mi') last_exe,
        b.enabled,
        b.accepted, 
        b.fixed,
        b.optimizer_cost,
        b.executions,
        b.cpu_time,
        b.buffer_Gets,
        b.disk_Reads,
        CASE WHEN b.executions > 0 then
        ROUND((b.elapsed_time/b.executions)/1000000,1) 
        ELSE NULL
        END AS "seconds per execution",
        a.sql_id 
FROM DBA_SQL_PLAN_BASELINES b LEFT OUTER JOIN v$sql a
ON (b.plan_name = a.sql_plan_baseline)
WHERE b.sql_text LIKE 'SELECT * FROM( SELECT KLM.VIEWTYPE KLMTYPE , TS%';

Result may look like the following:

SQL_HANDLE	PLAN_NAME	ORIGIN	CREATED	LAST_MOD	LAST_EXE	ENABLED	ACCEPTED	FIXED	OPTIMIZER_COST	EXECUTIONS	CPU_TIME	BUFFER_GETS	DISK_READS	seconds pr execution	SQL_ID
SQL_5bdd86105a3f22a2	SQL_PLAN_5rrc621d3y8p2a8f06e05	MANUAL-LOAD	11.08.2016 14:42	12.08.2016 07:36	12.08.2016 07:36	YES	YES	YES	10948	27	35862546	7299186	297	1,4	5h0syvrgsjf0j
SQL_5bdd86105a3f22a2	SQL_PLAN_5rrc621d3y8p23e45ab6f	MANUAL-LOAD	11.08.2016 14:42	11.08.2016 14:47		NO	YES	NO	30537	1	3549461	434057	5371	10,8
SQL_5bdd86105a3f22a2	SQL_PLAN_5rrc621d3y8p28dd60076	MANUAL-LOAD	11.08.2016 14:42	11.08.2016 15:02		NO	YES	NO	1324	2	18519310636	1131813	0	9253,6

From the output above, we can see that the fixed plan is the most efficient, that's why it was marked as FIXED in the SMB.

For finding a specific plan name:

SELECT plan_name,
         sql_handle,
         creator,
         origin,
         TO_CHAR (created, 'dd.mm.yyyy hh24:mi') "created",
         TO_CHAR (last_executed, 'dd.mm.yyyy hh24:mi') "lastexecuted",
         enabled,
         accepted,
         fixed,
         autopurge,
         module,
         ROUND (ELAPSED_TIME / 1000000) "duration in seconds",
         cpu_time,
         buffer_gets,
         disk_reads
    FROM DBA_SQL_PLAN_BASELINES
WHERE plan_name='SQL_PLAN_asryr8hfgjd5hddf0c98b'

For finding all Plans created today:

SELECT plan_name,
         sql_handle,
         creator,
         origin,
         TO_CHAR (created, 'dd.mm.yyyy hh24:mi') "created",
         TO_CHAR (last_executed, 'dd.mm.yyyy hh24:mi') "lastexecuted",
         enabled,
         accepted,
         fixed,
         autopurge,
         module,
         ROUND (ELAPSED_TIME / 1000000) "duration in seconds",
         cpu_time,
         buffer_gets,
         disk_reads
    FROM DBA_SQL_PLAN_BASELINES
WHERE TO_CHAR (created, 'dd.mm.yyyy') = TRUNC (SYSDATE)