Function ExecInitPruningContext

src/backend/executor/execPartition.c:1978–2038

* Initialize a PartitionPruneContext for the given list of pruning steps. */

 * Initialize a PartitionPruneContext for the given list of pruning steps.
 */
static void
ExecInitPruningContext(PartitionPruneContext *context,
					   List *pruning_steps,
					   PartitionDesc partdesc,
					   PartitionKey partkey,
					   PlanState *planstate)
{
	int			n_steps;
	int			partnatts;
	ListCell   *lc;

	n_steps = list_length(pruning_steps);

	context->strategy = partkey->strategy;
	context->partnatts = partnatts = partkey->partnatts;
	context->nparts = partdesc->nparts;
	context->boundinfo = partdesc->boundinfo;
	context->partcollation = partkey->partcollation;
	context->partsupfunc = partkey->partsupfunc;

	/* We'll look up type-specific support functions as needed */
	context->stepcmpfuncs = (FmgrInfo *)
		palloc0(sizeof(FmgrInfo) * n_steps * partnatts);

	context->ppccontext = CurrentMemoryContext;
	context->planstate = planstate;

	/* Initialize expression state for each expression we need */
	context->exprstates = (ExprState **)
		palloc0(sizeof(ExprState *) * n_steps * partnatts);
	foreach(lc, pruning_steps)
	{
		PartitionPruneStepOp *step = (PartitionPruneStepOp *) lfirst(lc);
		ListCell   *lc2;
		int			keyno;

		/* not needed for other step kinds */
		if (!IsA(step, PartitionPruneStepOp))
			continue;

		Assert(list_length(step->exprs) <= partnatts);

		keyno = 0;
		foreach(lc2, step->exprs)
		{
			Expr	   *expr = (Expr *) lfirst(lc2);

			/* not needed for Consts */
			if (!IsA(expr, Const))
			{
				int			stateidx = PruneCxtStateIdx(partnatts,
														step->step.step_id,
														keyno);

				context->exprstates[stateidx] =
					ExecInitExpr(expr, context->planstate);
			}
			keyno++;