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Amazon Redshift
Database Developer Guide (API Version 2012-12-01)

STL_MERGEJOIN

Analyzes merge join execution steps for queries.

This table is visible to all users. Superusers can see all rows; regular users can see only their own data. For more information, see Visibility of Data in System Tables and Views.

Table Columns

Column Name Data Type Description
userid integer ID of the user who generated the entry.
query integer Query ID. The query column can be used to join other system tables and views.
slice integer Number that identifies the slice where the query was running.
segment integer Number that identifies the query segment.
step integer Query step that executed.
starttime timestamp Time in UTC that the query started executing, with 6 digits of precision for fractional seconds. For example: 2009-06-12 11:29:19.131358.
endtime timestamp Time in UTC that the query finished executing, with 6 digits of precision for fractional seconds. For example: 2009-06-12 11:29:19.131358.
tasknum integer Number of the query task process that was assigned to execute the step.
rows bigint Total number of rows that were processed.
tbl integer Table ID. This is the ID for the inner table that was used in the merge join.

Sample Queries

The following example returns merge join results for the most recent query.

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select sum(s.qtysold), e.eventname from event e, listing l, sales s where e.eventid=l.eventid and l.listid= s.listid group by e.eventname; select * from stl_mergejoin where query=pg_last_query_id();
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userid | query | slice | segment | step | starttime | endtime | tasknum | rows | tbl --------+-------+-------+---------+------+---------------------+---------------------+---------+------+----- 100 | 27399 | 3 | 4 | 4 | 2013-10-02 16:30:41 | 2013-10-02 16:30:41 | 19 |43428 | 240 100 | 27399 | 0 | 4 | 4 | 2013-10-02 16:30:41 | 2013-10-02 16:30:41 | 19 |43159 | 240 100 | 27399 | 2 | 4 | 4 | 2013-10-02 16:30:41 | 2013-10-02 16:30:41 | 19 |42778 | 240 100 | 27399 | 1 | 4 | 4 | 2013-10-02 16:30:41 | 2013-10-02 16:30:41 | 19 |43091 | 240