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Posted to derby-dev@db.apache.org by "Mamta A. Satoor (JIRA)" <ji...@apache.org> on 2013/02/05 07:46:12 UTC
[jira] [Commented] (DERBY-6045) in list multi-probe by primary key
not chosen on tables with >256 rows
[ https://issues.apache.org/jira/browse/DERBY-6045?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13571092#comment-13571092 ]
Mamta A. Satoor commented on DERBY-6045:
----------------------------------------
BTW, I tried the little experiment I tried on the trunk(on 25/Jan/13) on 10.9.1.0 release and saw the same behavior as trunk. But on 10.8.1.1 and 10.8.1.2, I saw that even after 25 rows, we still use index scan rather than switching to table scan. So something has changed between 10.8 and 10.9 release apparently which has changed the behavior.
> in list multi-probe by primary key not chosen on tables with >256 rows
> ----------------------------------------------------------------------
>
> Key: DERBY-6045
> URL: https://issues.apache.org/jira/browse/DERBY-6045
> Project: Derby
> Issue Type: Bug
> Components: Store
> Affects Versions: 10.9.1.0
> Environment: Linux Debian 6.0.5
> Reporter: Tony Brusseau
> Priority: Critical
>
> I have a table with a long integer primary key field and 11 million rows. I seem to be unable to load large chunks of rows via id in a reasonably efficient manner.
> 1. If I do individual lookups via the primary key, then a fast indexed lookup occurs. However, if I do large numbers of such queries, then the time is overwhelmed by round-trip overhead which makes everything incredibly slow.
> 2. If I use a single query with a disjunction of the primary keys of interest, then a table scan is performed (even if the clause only contains 1-3 items), which walks over 11 million rows...incredibly inefficient.
> 3. If I use an IN clause, then a table scan is performed (even if the clause only contains 1-3 items), which walks over 11 million rows...incredibly inefficient.
> I'm guessing that this might have something to do with the fact that I'm using large integers and really big numbers that don't start anywhere at or about 1 for my keys. Could this possibly be confusing the optimizer?
> Here are the unlimited query plans for the 3 cases that I enumerated:
> *********************************************************************************************
> [EL Fine]: 2013-01-17 11:09:53.384--ServerSession(582235416)--Connection(1430986883)--Thread(Thread["Initial Lisp Listener",5,SubL Thread Group])--SELECT TERM_ID, ARG0, ARG1, ARG2, ARG3, FORMULA_HASH, FORMULA_LENGTH, FORMULA_TYPE, KB_STATUS FROM KB.FORMULA_TERM WHERE (TERM_ID = ?)
> bind => [2251799814033500]
> Thu Jan 17 11:09:53 CST 2013 Thread["Initial Lisp Listener",5,SubL Thread Group] (XID = 4711079), (SESSIONID = 3), SELECT TERM_ID, ARG0, ARG1, ARG2, ARG3, FORMULA_HASH, FORMULA_LENGTH, FORMULA_TYPE, KB_STATUS FROM KB.FORMULA_TERM WHERE (TERM_ID = ?) ******* Project-Restrict ResultSet (3):
> Number of opens = 1
> Rows seen = 1
> Rows filtered = 0
> restriction = false
> projection = true
> constructor time (milliseconds) = 0
> open time (milliseconds) = 0
> next time (milliseconds) = 0
> close time (milliseconds) = 0
> restriction time (milliseconds) = 0
> projection time (milliseconds) = 0
> optimizer estimated row count: 1.00
> optimizer estimated cost: 6.59
> Source result set:
> Index Row to Base Row ResultSet for FORMULA_TERM:
> Number of opens = 1
> Rows seen = 1
> Columns accessed from heap = {1, 2, 3, 4, 5, 6, 7, 8}
> constructor time (milliseconds) = 0
> open time (milliseconds) = 0
> next time (milliseconds) = 0
> close time (milliseconds) = 0
> optimizer estimated row count: 1.00
> optimizer estimated cost: 6.59
> Index Scan ResultSet for FORMULA_TERM using constraint KB_FORMULA_TERM_TERM_ID_PK at read committed isolation level using share row locking chosen by the optimizer
> Number of opens = 1
> Rows seen = 1
> Rows filtered = 0
> Fetch Size = 1
> constructor time (milliseconds) = 0
> open time (milliseconds) = 0
> next time (milliseconds) = 0
> close time (milliseconds) = 0
> next time in milliseconds/row = 0
> scan information:
> Bit set of columns fetched=All
> Number of columns fetched=2
> Number of deleted rows visited=0
> Number of pages visited=3
> Number of rows qualified=1
> Number of rows visited=1
> Scan type=btree
> Tree height=-1
> start position:
> >= on first 1 column(s).
> Ordered null semantics on the following columns:
> stop position:
> > on first 1 column(s).
> Ordered null semantics on the following columns:
> qualifiers:
> None
> optimizer estimated row count: 1.00
> optimizer estimated cost: 6.59
> [EL Fine]: 2013-01-17 11:01:00.732--ServerSession(1237006689)--Connection(927179828)--Thread(Thread["Initial Lisp Listener",5,SubL Thread Group])--SELECT TERM_ID, ARG0, ARG1, ARG2, ARG3, FORMULA_HASH, FORMULA_LENGTH, FORMULA_TYPE, KB_STATUS FROM KB.FORMULA_TERM WHERE (((TERM_ID = ?) OR (TERM_ID = ?)) OR (TERM_ID = ?))
> bind => [2251799814033500, 2251799814033501, 2251799814033499]
> Thu Jan 17 11:01:10 CST 2013 Thread["Initial Lisp Listener",5,SubL Thread Group] (XID = 4711078), (SESSIONID = 3), SELECT TERM_ID, ARG0, ARG1, ARG2, ARG3, FORMULA_HASH, FORMULA_LENGTH, FORMULA_TYPE, KB_STATUS FROM KB.FORMULA_TERM WHERE (((TERM_ID = ?) OR (TERM_ID = ?)) OR (TERM_ID = ?)) ******* Project-Restrict ResultSet (3):
> Number of opens = 1
> Rows seen = 3
> Rows filtered = 0
> restriction = false
> projection = true
> constructor time (milliseconds) = 0
> open time (milliseconds) = 0
> next time (milliseconds) = 0
> close time (milliseconds) = 0
> restriction time (milliseconds) = 0
> projection time (milliseconds) = 0
> optimizer estimated row count: 1176730.30
> optimizer estimated cost: 5931065.54
> Source result set:
> Project-Restrict ResultSet (2):
> Number of opens = 1
> Rows seen = 11767298
> Rows filtered = 11767295
> restriction = true
> projection = false
> constructor time (milliseconds) = 0
> open time (milliseconds) = 0
> next time (milliseconds) = 0
> close time (milliseconds) = 0
> restriction time (milliseconds) = 0
> projection time (milliseconds) = 0
> optimizer estimated row count: 1176730.30
> optimizer estimated cost: 5931065.54
> Source result set:
> Table Scan ResultSet for FORMULA_TERM at read committed isolation level using instantaneous share row locking chosen by the optimizer
> Number of opens = 1
> Rows seen = 11767298
> Rows filtered = 0
> Fetch Size = 16
> constructor time (milliseconds) = 0
> open time (milliseconds) = 0
> next time (milliseconds) = 0
> close time (milliseconds) = 0
> next time in milliseconds/row = 0
> scan information:
> Bit set of columns fetched=All
> Number of columns fetched=9
> Number of pages visited=34358
> Number of rows qualified=11767298
> Number of rows visited=11767298
> Scan type=heap
> start position:
> null
> stop position:
> null
> qualifiers:
> None
> optimizer estimated row count: 1176730.30
> optimizer estimated cost: 5931065.54
> [EL Fine]: 2013-01-17 11:27:00.627--ServerSession(1237006689)--Connection(1688096771)--Thread(Thread["Initial Lisp Listener",5,SubL Thread Group])--SELECT TERM_ID, ARG0, ARG1, ARG2, ARG3, FORMULA_HASH, FORMULA_LENGTH, FORMULA_TYPE, KB_STATUS FROM KB.FORMULA_TERM WHERE (TERM_ID IN (?,?,?))
> bind => [2251799814033500, 2251799814033501, 2251799814033499]
> Thu Jan 17 11:47:26 CST 2013 Thread["Initial Lisp Listener",5,SubL Thread Group] (XID = 4711080), (SESSIONID = 3), SELECT TERM_ID, ARG0, ARG1, ARG2, ARG3, FORMULA_HASH, FORMULA_LENGTH, FORMULA_TYPE, KB_STATUS FROM KB.FORMULA_TERM WHERE (TERM_ID IN (?,?,?)) ******* Project-Restrict ResultSet (3):
> Number of opens = 1
> Rows seen = 3
> Rows filtered = 0
> restriction = false
> projection = true
> constructor time (milliseconds) = 0
> open time (milliseconds) = 0
> next time (milliseconds) = 0
> close time (milliseconds) = 0
> restriction time (milliseconds) = 0
> projection time (milliseconds) = 0
> optimizer estimated row count: 1176730.30
> optimizer estimated cost: 5931065.54
> Source result set:
> Project-Restrict ResultSet (2):
> Number of opens = 1
> Rows seen = 11767298
> Rows filtered = 11767295
> restriction = true
> projection = false
> constructor time (milliseconds) = 0
> open time (milliseconds) = 0
> next time (milliseconds) = 0
> close time (milliseconds) = 0
> restriction time (milliseconds) = 0
> projection time (milliseconds) = 0
> optimizer estimated row count: 1176730.30
> optimizer estimated cost: 5931065.54
> Source result set:
> Table Scan ResultSet for FORMULA_TERM at read committed isolation level using instantaneous share row locking chosen by the optimizer
> Number of opens = 1
> Rows seen = 11767298
> Rows filtered = 0
> Fetch Size = 16
> constructor time (milliseconds) = 0
> open time (milliseconds) = 0
> next time (milliseconds) = 0
> close time (milliseconds) = 0
> next time in milliseconds/row = 0
> scan information:
> Bit set of columns fetched=All
> Number of columns fetched=9
> Number of pages visited=34358
> Number of rows qualified=11767298
> Number of rows visited=11767298
> Scan type=heap
> start position:
> null
> stop position:
> null
> qualifiers:
> None
> optimizer estimated row count: 1176730.30
> optimizer estimated cost: 5931065.54
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