database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-08 11:42:09 +03:00
Code Activity

Don't generate EEOP_*_FETCHSOME operations for slots know to be virtual.

Browse Source 
That avoids unnecessary work during both interpreted execution, and
JIT compiled expression evaluation. Both benefit from fewer expression
steps needing be processed, and for interpreted execution there now is
a fastpath dedicated to just fetching a value from a virtual
slot. That's e.g. beneficial for hashjoins over nodes that perform
projections, as the hashed columns are currently fetched individually.

Author: Soumyadeep Chakraborty, Andres Freund
Discussion: https://postgr.es/m/CAE-ML+9OKSN71+mHtfMD-L24oDp8dGTfaVjDU6U+j+FNAW5kRQ@mail.gmail.com
This commit is contained in:
Andres Freund
2019-09-30 16:06:16 -07:00
parent 34c9c53bb0
commit 36d22dd95b
3 changed files with 160 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files

43
src/backend/executor/execExpr.c
View File

@ -65,7 +65,7 @@ static void ExecInitFunc(ExprEvalStep *scratch, Expr *node, List *args,
static void ExecInitExprSlots(ExprState *state, Node *node);
static void ExecPushExprSlots(ExprState *state, LastAttnumInfo *info);
static bool get_last_attnums_walker(Node *node, LastAttnumInfo *info);
static void ExecComputeSlotInfo(ExprState *state, ExprEvalStep *op);
static bool ExecComputeSlotInfo(ExprState *state, ExprEvalStep *op);
static void ExecInitWholeRowVar(ExprEvalStep *scratch, Var *variable,
ExprState *state);
static void ExecInitSubscriptingRef(ExprEvalStep *scratch,
@ -2285,8 +2285,8 @@ ExecPushExprSlots(ExprState *state, LastAttnumInfo *info)
scratch.d.fetch.fixed = false;
scratch.d.fetch.kind = NULL;
scratch.d.fetch.known_desc = NULL;
ExecComputeSlotInfo(state, &scratch);
ExprEvalPushStep(state, &scratch);
if (ExecComputeSlotInfo(state, &scratch))
ExprEvalPushStep(state, &scratch);
}
if (info->last_outer > 0)
{
@ -2295,8 +2295,8 @@ ExecPushExprSlots(ExprState *state, LastAttnumInfo *info)
scratch.d.fetch.fixed = false;
scratch.d.fetch.kind = NULL;
scratch.d.fetch.known_desc = NULL;
ExecComputeSlotInfo(state, &scratch);
ExprEvalPushStep(state, &scratch);
if (ExecComputeSlotInfo(state, &scratch))
ExprEvalPushStep(state, &scratch);
}
if (info->last_scan > 0)
{
@ -2305,8 +2305,8 @@ ExecPushExprSlots(ExprState *state, LastAttnumInfo *info)
scratch.d.fetch.fixed = false;
scratch.d.fetch.kind = NULL;
scratch.d.fetch.known_desc = NULL;
ExecComputeSlotInfo(state, &scratch);
ExprEvalPushStep(state, &scratch);
if (ExecComputeSlotInfo(state, &scratch))
ExprEvalPushStep(state, &scratch);
}
}
@ -2364,14 +2364,21 @@ get_last_attnums_walker(Node *node, LastAttnumInfo *info)
* The goal is to determine whether a slot is 'fixed', that is, every
* evaluation of the expression will have the same type of slot, with an
* equivalent descriptor.
*
* Returns true if the the deforming step is required, false otherwise.
*/
static void
static bool
ExecComputeSlotInfo(ExprState *state, ExprEvalStep *op)
{
PlanState *parent = state->parent;
TupleDesc desc = NULL;
const TupleTableSlotOps *tts_ops = NULL;
bool isfixed = false;
ExprEvalOp opcode = op->opcode;
Assert(opcode == EEOP_INNER_FETCHSOME ||
opcode == EEOP_OUTER_FETCHSOME ||
opcode == EEOP_SCAN_FETCHSOME);
if (op->d.fetch.known_desc != NULL)
{
@ -2383,7 +2390,7 @@ ExecComputeSlotInfo(ExprState *state, ExprEvalStep *op)
{
isfixed = false;
}
else if (op->opcode == EEOP_INNER_FETCHSOME)
else if (opcode == EEOP_INNER_FETCHSOME)
{
PlanState *is = innerPlanState(parent);
@ -2403,7 +2410,7 @@ ExecComputeSlotInfo(ExprState *state, ExprEvalStep *op)
desc = ExecGetResultType(is);
}
}
else if (op->opcode == EEOP_OUTER_FETCHSOME)
else if (opcode == EEOP_OUTER_FETCHSOME)
{
PlanState *os = outerPlanState(parent);
@ -2423,7 +2430,7 @@ ExecComputeSlotInfo(ExprState *state, ExprEvalStep *op)
desc = ExecGetResultType(os);
}
}
else if (op->opcode == EEOP_SCAN_FETCHSOME)
else if (opcode == EEOP_SCAN_FETCHSOME)
{
desc = parent->scandesc;
@ -2446,6 +2453,12 @@ ExecComputeSlotInfo(ExprState *state, ExprEvalStep *op)
op->d.fetch.kind = NULL;
op->d.fetch.known_desc = NULL;
}
/* if the slot is known to always virtual we never need to deform */
if (op->d.fetch.fixed && op->d.fetch.kind == &TTSOpsVirtual)
return false;
return true;
}
/*
@ -3360,16 +3373,16 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
scratch.d.fetch.fixed = false;
scratch.d.fetch.known_desc = ldesc;
scratch.d.fetch.kind = lops;
ExecComputeSlotInfo(state, &scratch);
ExprEvalPushStep(state, &scratch);
if (ExecComputeSlotInfo(state, &scratch))
ExprEvalPushStep(state, &scratch);
scratch.opcode = EEOP_OUTER_FETCHSOME;
scratch.d.fetch.last_var = maxatt;
scratch.d.fetch.fixed = false;
scratch.d.fetch.known_desc = rdesc;
scratch.d.fetch.kind = rops;
ExecComputeSlotInfo(state, &scratch);
ExprEvalPushStep(state, &scratch);
if (ExecComputeSlotInfo(state, &scratch))
ExprEvalPushStep(state, &scratch);
/*
* Start comparing at the last field (least significant sort key). That's