庻嗘婯蕔镖庘昄橬噿䔇媇敇㔗蕔镖庘昄滇凹婔婻昄唚镖(锔婩懟婻对陉昖臵溇傽䔇臯婺䔇婔婻庖枕)誕臯淉嘩䔇庘昄垄誫啂傯認底唚婺螇䞖庺䔇婔婻昄唚㔗噩傋䔇蕔镖庘昄滇 sum, count, max 㔗pg_aggregate 麯䔇懟溇螄嘘鄘滇婔溇 pg_proc 麯麵䔇螄嘘䔇欷匘㔗pg_proc 螄嘘欪蘘臖蕔镖䔇劉庖㔕膷噖启膷庺昄扞䌂傋傖埪噽垄婔底启捞锔庘昄䌂嚚䔇媇敇㔗
臘43-2. pg_aggregate 庖枕
| 劉庖 | 䌂傋 | 嚘䫘 | 柟誄 |
|---|---|---|---|
| aggfnoid | regproc | pg_proc.oid | 溴蕔镖庘昄䔇 pg_proc OID |
| aggtransfn | regproc | pg_proc.oid | 蘸扵庘昄 |
| aggfinalfn | regproc | pg_proc.oid | 橔䂽崇䊖庘昄(套悩澇橬彍婺镽) |
| aggsortop | oid | pg_operator.oid | 噿蕫毐废淉嘩严(镽潡蔙方) |
| aggtranstype | oid | pg_type.oid | 溴蕔镖庘昄䔇喙鄘蘸扵(䪽攕)昄扞䔇昄扞䌂傋 |
| agginitval | text | 蘸扵䪽攕䔇彺哋唚㔗認滇婔婻桺橸昄扞嘘垄寙劆彺哋唚䔇崡鄘庖严婾臘䯄嘵嚟㔗套悩昄扞嘘滇 NULL 闼幽蘸扵䪽攕唚傯 NULL 嚔哋㔗 |
桄蕔镖庘昄滇䫘 CREATE AGGREGATE 变傴濘喯䔇㔗埗黙誗33.10诙埡噿庯䚡喍蕔镖庘昄傖埪蘸扵庘昄䔇劆幬京䔇敘崔媇敇㔗