I had thought that the Creation of the Index would do something equivalent to Analyze. I tried Analyze Verbose and it improved the scanner's ability to predict when an index would be useful.
Last week, I asked about visualizing B-tree "coverage". I think I meant "Can I see the histograms that Analyze creates?" Are they available anywhere? The docs mention them (bins) and I was hoping Analyze Verbose would show them to me.
TJ
Tom Lane wrote:
"TJ O'Donnell" <tjo@xxxxxxx> writes:
This I don't get. Why is an index scan not used? Isn't an index supposed to help when using > < >= <= too? Explain Analyze Select count(smiles) from structure where _c >= 30 Aggregate (cost=196033.74..196033.74 rows=1 width=32) (actual time=42133.432..42133.434 rows=1 loops=1) -> Seq Scan on structure (cost=0.00..191619.56 rows=1765669 width=32) (actual time=8050.437..42117.062 rows=1569 loops=1) Filter: (_c >= 30)
Have you ANALYZEd the table lately? That rowcount estimate is off by about three orders of magnitude :-(
regards, tom lane
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