Raw Metadata XML
<pkgmetadata>
<maintainer type="person">
<email>dan@d3fy.net</email>
<name>Dan Molik</name>
</maintainer>
<longdescription lang="en">
pg_qualstats is a PostgreSQL extension keeping statistics on predicates found
in WHERE statements and JOIN clauses.
This is useful if you want to be able to analyze what are the most-often
executed quals (predicates) on your database. The powa project makes use of
this to provide advances index suggestions.
It also allows you to identify correlated columns, by identifying which
columns are most frequently queried together.
The extension works by looking for known patterns in queries. Currently,
this includes:
- Binary OpExpr where at least one side is a column from a table. Whenever
possible, the predicate will be swaped so that CONST OP VAR expressions are
turned into VAR COMMUTED_OP CONST. AND and OR expression members are counted
as separate entries.
Ex: WHERE column1 = 2, WHERE column1 = column2, WHERE 3 = column3
- ScalarArrayOpExpr where the left side is a VAR, and the right side is an
array constant. Those will be counted one time per element in the array.
Ex: WHERE column1 IN (2, 3) will be counted as 2 occurences
for the (column1, '=') operator pair
- BooleanTest where the expression is a simple boolean column reference
Ex: WHERE column1 IS TRUE Please not that clauses like WHERE columns1,
WHERE NOT column1 won't be processed by pg_qualstats (yet)
</longdescription>
</pkgmetadata>