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authorTom Lane <tgl@sss.pgh.pa.us>2005-01-28 20:34:27 +0000
committerTom Lane <tgl@sss.pgh.pa.us>2005-01-28 20:34:27 +0000
commit875b0c62fabeafd65136ad5d6825274f983b8e88 (patch)
tree680fd5be04cdea754b90c7c21a7284621498b44b /src/tutorial
parent0bf2587df46f3b554d62f7628d1d474bda7ddfc5 (diff)
When dealing with multiple grouping columns coming from the same table,
clamp the estimated number of groups to table row count over 10, instead of table row count; this reflects a heuristic that people probably won't group over a near-unique set of columns, and the knowledge that we don't currently have any way to estimate the correlation of the columns better than guessing. This change creates a trivial plan change in one of the regression tests.
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