diff options
Diffstat (limited to 'src/backend/utils/cache/partcache.c')
| -rw-r--r-- | src/backend/utils/cache/partcache.c | 430 |
1 files changed, 430 insertions, 0 deletions
diff --git a/src/backend/utils/cache/partcache.c b/src/backend/utils/cache/partcache.c new file mode 100644 index 0000000..afa99c5 --- /dev/null +++ b/src/backend/utils/cache/partcache.c @@ -0,0 +1,430 @@ +/*------------------------------------------------------------------------- + * + * partcache.c + * Support routines for manipulating partition information cached in + * relcache + * + * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * IDENTIFICATION + * src/backend/utils/cache/partcache.c + * + *------------------------------------------------------------------------- +*/ +#include "postgres.h" + +#include "access/hash.h" +#include "access/htup_details.h" +#include "access/nbtree.h" +#include "access/relation.h" +#include "catalog/partition.h" +#include "catalog/pg_inherits.h" +#include "catalog/pg_opclass.h" +#include "catalog/pg_partitioned_table.h" +#include "miscadmin.h" +#include "nodes/makefuncs.h" +#include "nodes/nodeFuncs.h" +#include "optimizer/optimizer.h" +#include "partitioning/partbounds.h" +#include "rewrite/rewriteHandler.h" +#include "utils/builtins.h" +#include "utils/datum.h" +#include "utils/lsyscache.h" +#include "utils/memutils.h" +#include "utils/partcache.h" +#include "utils/rel.h" +#include "utils/syscache.h" + + +static void RelationBuildPartitionKey(Relation relation); +static List *generate_partition_qual(Relation rel); + +/* + * RelationGetPartitionKey -- get partition key, if relation is partitioned + * + * Note: partition keys are not allowed to change after the partitioned rel + * is created. RelationClearRelation knows this and preserves rd_partkey + * across relcache rebuilds, as long as the relation is open. Therefore, + * even though we hand back a direct pointer into the relcache entry, it's + * safe for callers to continue to use that pointer as long as they hold + * the relation open. + */ +PartitionKey +RelationGetPartitionKey(Relation rel) +{ + if (rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE) + return NULL; + + if (unlikely(rel->rd_partkey == NULL)) + RelationBuildPartitionKey(rel); + + return rel->rd_partkey; +} + +/* + * RelationBuildPartitionKey + * Build partition key data of relation, and attach to relcache + * + * Partitioning key data is a complex structure; to avoid complicated logic to + * free individual elements whenever the relcache entry is flushed, we give it + * its own memory context, a child of CacheMemoryContext, which can easily be + * deleted on its own. To avoid leaking memory in that context in case of an + * error partway through this function, the context is initially created as a + * child of CurTransactionContext and only re-parented to CacheMemoryContext + * at the end, when no further errors are possible. Also, we don't make this + * context the current context except in very brief code sections, out of fear + * that some of our callees allocate memory on their own which would be leaked + * permanently. + */ +static void +RelationBuildPartitionKey(Relation relation) +{ + Form_pg_partitioned_table form; + HeapTuple tuple; + bool isnull; + int i; + PartitionKey key; + AttrNumber *attrs; + oidvector *opclass; + oidvector *collation; + ListCell *partexprs_item; + Datum datum; + MemoryContext partkeycxt, + oldcxt; + int16 procnum; + + tuple = SearchSysCache1(PARTRELID, + ObjectIdGetDatum(RelationGetRelid(relation))); + + if (!HeapTupleIsValid(tuple)) + elog(ERROR, "cache lookup failed for partition key of relation %u", + RelationGetRelid(relation)); + + partkeycxt = AllocSetContextCreate(CurTransactionContext, + "partition key", + ALLOCSET_SMALL_SIZES); + MemoryContextCopyAndSetIdentifier(partkeycxt, + RelationGetRelationName(relation)); + + key = (PartitionKey) MemoryContextAllocZero(partkeycxt, + sizeof(PartitionKeyData)); + + /* Fixed-length attributes */ + form = (Form_pg_partitioned_table) GETSTRUCT(tuple); + key->strategy = form->partstrat; + key->partnatts = form->partnatts; + + /* + * We can rely on the first variable-length attribute being mapped to the + * relevant field of the catalog's C struct, because all previous + * attributes are non-nullable and fixed-length. + */ + attrs = form->partattrs.values; + + /* But use the hard way to retrieve further variable-length attributes */ + /* Operator class */ + datum = SysCacheGetAttr(PARTRELID, tuple, + Anum_pg_partitioned_table_partclass, &isnull); + Assert(!isnull); + opclass = (oidvector *) DatumGetPointer(datum); + + /* Collation */ + datum = SysCacheGetAttr(PARTRELID, tuple, + Anum_pg_partitioned_table_partcollation, &isnull); + Assert(!isnull); + collation = (oidvector *) DatumGetPointer(datum); + + /* Expressions */ + datum = SysCacheGetAttr(PARTRELID, tuple, + Anum_pg_partitioned_table_partexprs, &isnull); + if (!isnull) + { + char *exprString; + Node *expr; + + exprString = TextDatumGetCString(datum); + expr = stringToNode(exprString); + pfree(exprString); + + /* + * Run the expressions through const-simplification since the planner + * will be comparing them to similarly-processed qual clause operands, + * and may fail to detect valid matches without this step; fix + * opfuncids while at it. We don't need to bother with + * canonicalize_qual() though, because partition expressions should be + * in canonical form already (ie, no need for OR-merging or constant + * elimination). + */ + expr = eval_const_expressions(NULL, expr); + fix_opfuncids(expr); + + oldcxt = MemoryContextSwitchTo(partkeycxt); + key->partexprs = (List *) copyObject(expr); + MemoryContextSwitchTo(oldcxt); + } + + /* Allocate assorted arrays in the partkeycxt, which we'll fill below */ + oldcxt = MemoryContextSwitchTo(partkeycxt); + key->partattrs = (AttrNumber *) palloc0(key->partnatts * sizeof(AttrNumber)); + key->partopfamily = (Oid *) palloc0(key->partnatts * sizeof(Oid)); + key->partopcintype = (Oid *) palloc0(key->partnatts * sizeof(Oid)); + key->partsupfunc = (FmgrInfo *) palloc0(key->partnatts * sizeof(FmgrInfo)); + + key->partcollation = (Oid *) palloc0(key->partnatts * sizeof(Oid)); + key->parttypid = (Oid *) palloc0(key->partnatts * sizeof(Oid)); + key->parttypmod = (int32 *) palloc0(key->partnatts * sizeof(int32)); + key->parttyplen = (int16 *) palloc0(key->partnatts * sizeof(int16)); + key->parttypbyval = (bool *) palloc0(key->partnatts * sizeof(bool)); + key->parttypalign = (char *) palloc0(key->partnatts * sizeof(char)); + key->parttypcoll = (Oid *) palloc0(key->partnatts * sizeof(Oid)); + MemoryContextSwitchTo(oldcxt); + + /* determine support function number to search for */ + procnum = (key->strategy == PARTITION_STRATEGY_HASH) ? + HASHEXTENDED_PROC : BTORDER_PROC; + + /* Copy partattrs and fill other per-attribute info */ + memcpy(key->partattrs, attrs, key->partnatts * sizeof(int16)); + partexprs_item = list_head(key->partexprs); + for (i = 0; i < key->partnatts; i++) + { + AttrNumber attno = key->partattrs[i]; + HeapTuple opclasstup; + Form_pg_opclass opclassform; + Oid funcid; + + /* Collect opfamily information */ + opclasstup = SearchSysCache1(CLAOID, + ObjectIdGetDatum(opclass->values[i])); + if (!HeapTupleIsValid(opclasstup)) + elog(ERROR, "cache lookup failed for opclass %u", opclass->values[i]); + + opclassform = (Form_pg_opclass) GETSTRUCT(opclasstup); + key->partopfamily[i] = opclassform->opcfamily; + key->partopcintype[i] = opclassform->opcintype; + + /* Get a support function for the specified opfamily and datatypes */ + funcid = get_opfamily_proc(opclassform->opcfamily, + opclassform->opcintype, + opclassform->opcintype, + procnum); + if (!OidIsValid(funcid)) + ereport(ERROR, + (errcode(ERRCODE_INVALID_OBJECT_DEFINITION), + errmsg("operator class \"%s\" of access method %s is missing support function %d for type %s", + NameStr(opclassform->opcname), + (key->strategy == PARTITION_STRATEGY_HASH) ? + "hash" : "btree", + procnum, + format_type_be(opclassform->opcintype)))); + + fmgr_info_cxt(funcid, &key->partsupfunc[i], partkeycxt); + + /* Collation */ + key->partcollation[i] = collation->values[i]; + + /* Collect type information */ + if (attno != 0) + { + Form_pg_attribute att = TupleDescAttr(relation->rd_att, attno - 1); + + key->parttypid[i] = att->atttypid; + key->parttypmod[i] = att->atttypmod; + key->parttypcoll[i] = att->attcollation; + } + else + { + if (partexprs_item == NULL) + elog(ERROR, "wrong number of partition key expressions"); + + key->parttypid[i] = exprType(lfirst(partexprs_item)); + key->parttypmod[i] = exprTypmod(lfirst(partexprs_item)); + key->parttypcoll[i] = exprCollation(lfirst(partexprs_item)); + + partexprs_item = lnext(key->partexprs, partexprs_item); + } + get_typlenbyvalalign(key->parttypid[i], + &key->parttyplen[i], + &key->parttypbyval[i], + &key->parttypalign[i]); + + ReleaseSysCache(opclasstup); + } + + ReleaseSysCache(tuple); + + /* Assert that we're not leaking any old data during assignments below */ + Assert(relation->rd_partkeycxt == NULL); + Assert(relation->rd_partkey == NULL); + + /* + * Success --- reparent our context and make the relcache point to the + * newly constructed key + */ + MemoryContextSetParent(partkeycxt, CacheMemoryContext); + relation->rd_partkeycxt = partkeycxt; + relation->rd_partkey = key; +} + +/* + * RelationGetPartitionQual + * + * Returns a list of partition quals + */ +List * +RelationGetPartitionQual(Relation rel) +{ + /* Quick exit */ + if (!rel->rd_rel->relispartition) + return NIL; + + return generate_partition_qual(rel); +} + +/* + * get_partition_qual_relid + * + * Returns an expression tree describing the passed-in relation's partition + * constraint. + * + * If the relation is not found, or is not a partition, or there is no + * partition constraint, return NULL. We must guard against the first two + * cases because this supports a SQL function that could be passed any OID. + * The last case can happen even if relispartition is true, when a default + * partition is the only partition. + */ +Expr * +get_partition_qual_relid(Oid relid) +{ + Expr *result = NULL; + + /* Do the work only if this relation exists and is a partition. */ + if (get_rel_relispartition(relid)) + { + Relation rel = relation_open(relid, AccessShareLock); + List *and_args; + + and_args = generate_partition_qual(rel); + + /* Convert implicit-AND list format to boolean expression */ + if (and_args == NIL) + result = NULL; + else if (list_length(and_args) > 1) + result = makeBoolExpr(AND_EXPR, and_args, -1); + else + result = linitial(and_args); + + /* Keep the lock, to allow safe deparsing against the rel by caller. */ + relation_close(rel, NoLock); + } + + return result; +} + +/* + * generate_partition_qual + * + * Generate partition predicate from rel's partition bound expression. The + * function returns a NIL list if there is no predicate. + * + * We cache a copy of the result in the relcache entry, after constructing + * it using the caller's context. This approach avoids leaking any data + * into long-lived cache contexts, especially if we fail partway through. + */ +static List * +generate_partition_qual(Relation rel) +{ + HeapTuple tuple; + MemoryContext oldcxt; + Datum boundDatum; + bool isnull; + List *my_qual = NIL, + *result = NIL; + Oid parentrelid; + Relation parent; + + /* Guard against stack overflow due to overly deep partition tree */ + check_stack_depth(); + + /* If we already cached the result, just return a copy */ + if (rel->rd_partcheckvalid) + return copyObject(rel->rd_partcheck); + + /* + * Grab at least an AccessShareLock on the parent table. Must do this + * even if the partition has been partially detached, because transactions + * concurrent with the detach might still be trying to use a partition + * descriptor that includes it. + */ + parentrelid = get_partition_parent(RelationGetRelid(rel), true); + parent = relation_open(parentrelid, AccessShareLock); + + /* Get pg_class.relpartbound */ + tuple = SearchSysCache1(RELOID, RelationGetRelid(rel)); + if (!HeapTupleIsValid(tuple)) + elog(ERROR, "cache lookup failed for relation %u", + RelationGetRelid(rel)); + + boundDatum = SysCacheGetAttr(RELOID, tuple, + Anum_pg_class_relpartbound, + &isnull); + if (!isnull) + { + PartitionBoundSpec *bound; + + bound = castNode(PartitionBoundSpec, + stringToNode(TextDatumGetCString(boundDatum))); + + my_qual = get_qual_from_partbound(parent, bound); + } + + ReleaseSysCache(tuple); + + /* Add the parent's quals to the list (if any) */ + if (parent->rd_rel->relispartition) + result = list_concat(generate_partition_qual(parent), my_qual); + else + result = my_qual; + + /* + * Change Vars to have partition's attnos instead of the parent's. We do + * this after we concatenate the parent's quals, because we want every Var + * in it to bear this relation's attnos. It's safe to assume varno = 1 + * here. + */ + result = map_partition_varattnos(result, 1, rel, parent); + + /* Assert that we're not leaking any old data during assignments below */ + Assert(rel->rd_partcheckcxt == NULL); + Assert(rel->rd_partcheck == NIL); + + /* + * Save a copy in the relcache. The order of these operations is fairly + * critical to avoid memory leaks and ensure that we don't leave a corrupt + * relcache entry if we fail partway through copyObject. + * + * If, as is definitely possible, the partcheck list is NIL, then we do + * not need to make a context to hold it. + */ + if (result != NIL) + { + rel->rd_partcheckcxt = AllocSetContextCreate(CacheMemoryContext, + "partition constraint", + ALLOCSET_SMALL_SIZES); + MemoryContextCopyAndSetIdentifier(rel->rd_partcheckcxt, + RelationGetRelationName(rel)); + oldcxt = MemoryContextSwitchTo(rel->rd_partcheckcxt); + rel->rd_partcheck = copyObject(result); + MemoryContextSwitchTo(oldcxt); + } + else + rel->rd_partcheck = NIL; + rel->rd_partcheckvalid = true; + + /* Keep the parent locked until commit */ + relation_close(parent, NoLock); + + /* Return the working copy to the caller */ + return result; +} |