Обсуждение: Where is the filter?
When I use 'select * from t where a = 1'; And I debug to find where the 'a = 1' is used,
when I arrive ExecScan in src/backend/executor/execScan.c, line 158, where this 'a = 1' is
stored in?
jacktby@gmail.com
On Sat, Feb 4, 2023 at 11:29 PM jacktby@gmail.com <jacktby@gmail.com> wrote: > When I use 'select * from t where a = 1'; And I debug to find where the 'a = 1' is used, > when I arrive ExecScan in src/backend/executor/execScan.c, line 158, where this 'a = 1' is > stored in? It depends somewhat on what query plan you got. For instance if it was a Seq Scan then it will be a filter-condition, or "qual", and the call to ExecQual() later in ExecScan() will be responsible for evaluating it. But if you are using an index scan, then it will probably become an index qual, and those are passed down into the index machinery and internally handled by the index AM. It's a good idea when you're debugging this sort of thing to start by looking at the EXPLAIN or EXPLAIN ANALYZE output, and perhaps also the output with debug_print_plan = true. -- Robert Haas EDB: http://www.enterprisedb.com