diff options
Diffstat (limited to 'src/backend/executor/nodeAgg.c')
| -rw-r--r-- | src/backend/executor/nodeAgg.c | 65 |
1 files changed, 40 insertions, 25 deletions
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c index 6543ecebd3e..40d8ec9db46 100644 --- a/src/backend/executor/nodeAgg.c +++ b/src/backend/executor/nodeAgg.c @@ -248,9 +248,9 @@ typedef struct AggStatePerTransData /* * Link to an Aggref expr this state value is for. * - * There can be multiple Aggref's sharing the same state value, as long as - * the inputs and transition function are identical. This points to the - * first one of them. + * There can be multiple Aggref's sharing the same state value, so long as + * the inputs and transition functions are identical and the final + * functions are not read-write. This points to the first one of them. */ Aggref *aggref; @@ -419,8 +419,8 @@ typedef struct AggStatePerAggData Oid finalfn_oid; /* - * fmgr lookup data for final function --- only valid when finalfn_oid oid - * is not InvalidOid. + * fmgr lookup data for final function --- only valid when finalfn_oid is + * not InvalidOid. */ FmgrInfo finalfn; @@ -439,6 +439,11 @@ typedef struct AggStatePerAggData int16 resulttypeLen; bool resulttypeByVal; + /* + * "sharable" is false if this agg cannot share state values with other + * aggregates because the final function is read-write. + */ + bool sharable; } AggStatePerAggData; /* @@ -572,6 +577,7 @@ static void build_pertrans_for_aggref(AggStatePerTrans pertrans, static int find_compatible_peragg(Aggref *newagg, AggState *aggstate, int lastaggno, List **same_input_transnos); static int find_compatible_pertrans(AggState *aggstate, Aggref *newagg, + bool sharable, Oid aggtransfn, Oid aggtranstype, Oid aggserialfn, Oid aggdeserialfn, Datum initValue, bool initValueIsNull, @@ -3105,6 +3111,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags) AclResult aclresult; Oid transfn_oid, finalfn_oid; + bool sharable; Oid serialfn_oid, deserialfn_oid; Expr *finalfnexpr; @@ -3177,6 +3184,15 @@ ExecInitAgg(Agg *node, EState *estate, int eflags) else peragg->finalfn_oid = finalfn_oid = aggform->aggfinalfn; + /* + * If finalfn is marked read-write, we can't share transition states; + * but it is okay to share states for AGGMODIFY_SHARABLE aggs. Also, + * if we're not executing the finalfn here, we can share regardless. + */ + sharable = (aggform->aggfinalmodify != AGGMODIFY_READ_WRITE) || + (finalfn_oid == InvalidOid); + peragg->sharable = sharable; + serialfn_oid = InvalidOid; deserialfn_oid = InvalidOid; @@ -3315,11 +3331,12 @@ ExecInitAgg(Agg *node, EState *estate, int eflags) * 2. Build working state for invoking the transition function, or * look up previously initialized working state, if we can share it. * - * find_compatible_peragg() already collected a list of per-Trans's - * with the same inputs. Check if any of them have the same transition - * function and initial value. + * find_compatible_peragg() already collected a list of sharable + * per-Trans's with the same inputs. Check if any of them have the + * same transition function and initial value. */ existing_transno = find_compatible_pertrans(aggstate, aggref, + sharable, transfn_oid, aggtranstype, serialfn_oid, deserialfn_oid, initValue, initValueIsNull, @@ -3724,10 +3741,10 @@ GetAggInitVal(Datum textInitVal, Oid transtype) * with this one, with the same input parameters. If no compatible aggregate * can be found, returns -1. * - * As a side-effect, this also collects a list of existing per-Trans structs - * with matching inputs. If no identical Aggref is found, the list is passed - * later to find_compatible_pertrans, to see if we can at least reuse the - * state value of another aggregate. + * As a side-effect, this also collects a list of existing, sharable per-Trans + * structs with matching inputs. If no identical Aggref is found, the list is + * passed later to find_compatible_pertrans, to see if we can at least reuse + * the state value of another aggregate. */ static int find_compatible_peragg(Aggref *newagg, AggState *aggstate, @@ -3785,11 +3802,15 @@ find_compatible_peragg(Aggref *newagg, AggState *aggstate, } /* - * Not identical, but it had the same inputs. Return it to the caller, - * in case we can re-use its per-trans state. + * Not identical, but it had the same inputs. If the final function + * permits sharing, return its transno to the caller, in case we can + * re-use its per-trans state. (If there's already sharing going on, + * we might report a transno more than once. find_compatible_pertrans + * is cheap enough that it's not worth spending cycles to avoid that.) */ - *same_input_transnos = lappend_int(*same_input_transnos, - peragg->transno); + if (peragg->sharable) + *same_input_transnos = lappend_int(*same_input_transnos, + peragg->transno); } return -1; @@ -3804,7 +3825,7 @@ find_compatible_peragg(Aggref *newagg, AggState *aggstate, * verified to match.) */ static int -find_compatible_pertrans(AggState *aggstate, Aggref *newagg, +find_compatible_pertrans(AggState *aggstate, Aggref *newagg, bool sharable, Oid aggtransfn, Oid aggtranstype, Oid aggserialfn, Oid aggdeserialfn, Datum initValue, bool initValueIsNull, @@ -3812,14 +3833,8 @@ find_compatible_pertrans(AggState *aggstate, Aggref *newagg, { ListCell *lc; - /* - * For the moment, never try to share transition states between different - * ordered-set aggregates. This is necessary because the finalfns of the - * built-in OSAs (see orderedsetaggs.c) are destructive of their - * transition states. We should fix them so we can allow this, but not - * losing performance in the normal non-shared case will take some work. - */ - if (AGGKIND_IS_ORDERED_SET(newagg->aggkind)) + /* If this aggregate can't share transition states, give up */ + if (!sharable) return -1; foreach(lc, transnos) |