ANALYZE after CREATE TABLE AS SELECT...
Hi,
When I create a table with "CREATE TABLE name AS SELECT." statement and
immediately afterward use this new table in a query does it make sense to
run ANALYZE on the table in between? It appears that postgres should be
able to collect very detailed statistics while emitting the table but I am
not sure if this is done.
Thanks
Simon
Semyon Reyfman wrote:
When I create a table with "CREATE TABLE name AS SELECT." statement and
immediately afterward use this new table in a query does it make sense to
run ANALYZE on the table in between? It appears that postgres should be
able to collect very detailed statistics while emitting the table but I am
not sure if this is done.
It isn't. It also doesn't create any indexes, which you might want to
do before analyze.
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�lvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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On 2/26/15 5:23 PM, Alvaro Herrera wrote:
Semyon Reyfman wrote:
When I create a table with "CREATE TABLE name AS SELECT." statement and
immediately afterward use this new table in a query does it make sense to
run ANALYZE on the table in between? It appears that postgres should be
able to collect very detailed statistics while emitting the table but I am
not sure if this is done.It isn't. It also doesn't create any indexes, which you might want to
do before analyze.
Is it necessary to create indexes before analyzing?
I usually do, just to be safe, but I thought statistics were based
solely on sampling of the heap.
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- David Steele
david@pgmasters.net
David Steele <david@pgmasters.net> writes:
On 2/26/15 5:23 PM, Alvaro Herrera wrote:
It isn't. It also doesn't create any indexes, which you might want to
do before analyze.
Is it necessary to create indexes before analyzing?
I usually do, just to be safe, but I thought statistics were based
solely on sampling of the heap.
ANALYZE pays no attention to plain indexes. If you have any expression
indexes, it will collect stats for those expressions.
regards, tom lane
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