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Diffstat (limited to 'src/backend/access/common/tupdesc.c')
| -rw-r--r-- | src/backend/access/common/tupdesc.c | 398 |
1 files changed, 398 insertions, 0 deletions
diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c new file mode 100644 index 00000000000..527eb5113df --- /dev/null +++ b/src/backend/access/common/tupdesc.c @@ -0,0 +1,398 @@ +/*------------------------------------------------------------------------- + * + * tupdesc.c-- + * POSTGRES tuple descriptor support code + * + * Copyright (c) 1994, Regents of the University of California + * + * + * IDENTIFICATION + * $Header: /cvsroot/pgsql/src/backend/access/common/tupdesc.c,v 1.1.1.1 1996/07/09 06:21:10 scrappy Exp $ + * + * NOTES + * some of the executor utility code such as "ExecTypeFromTL" should be + * moved here. + * + *------------------------------------------------------------------------- + */ +#include <stdio.h> /* for sprintf() */ +#include <ctype.h> +#include <string.h> + +#include "postgres.h" + +#include "nodes/pg_list.h" +#include "nodes/parsenodes.h" + +#include "access/attnum.h" +#include "access/htup.h" +#include "access/tupdesc.h" + +#include "utils/builtins.h" +#include "utils/elog.h" /* XXX generate exceptions instead */ +#include "utils/palloc.h" + +#include "utils/syscache.h" +#include "catalog/pg_type.h" + +#include "nodes/primnodes.h" + +#include "parser/catalog_utils.h" + +/* ---------------------------------------------------------------- + * CreateTemplateTupleDesc + * + * This function allocates and zeros a tuple descriptor structure. + * ---------------------------------------------------------------- + */ +TupleDesc +CreateTemplateTupleDesc(int natts) +{ + uint32 size; + TupleDesc desc; + + /* ---------------- + * sanity checks + * ---------------- + */ + AssertArg(natts >= 1); + + /* ---------------- + * allocate enough memory for the tuple descriptor and + * zero it as TupleDescInitEntry assumes that the descriptor + * is filled with NULL pointers. + * ---------------- + */ + size = natts * sizeof (AttributeTupleForm); + desc = (TupleDesc) palloc(sizeof(struct tupleDesc)); + desc->attrs = (AttributeTupleForm*) palloc(size); + memset(desc->attrs, 0, size); + + desc->natts = natts; + + return (desc); +} + +/* ---------------------------------------------------------------- + * CreateTupleDesc + * + * This function allocates a new TupleDesc from AttributeTupleForm array + * ---------------------------------------------------------------- + */ +TupleDesc +CreateTupleDesc(int natts, AttributeTupleForm* attrs) +{ + TupleDesc desc; + + /* ---------------- + * sanity checks + * ---------------- + */ + AssertArg(natts >= 1); + + desc = (TupleDesc) palloc(sizeof(struct tupleDesc)); + desc->attrs = attrs; + desc->natts = natts; + + + return (desc); +} + +/* ---------------------------------------------------------------- + * CreateTupleDescCopy + * + * This function creates a new TupleDesc by copying from an existing + * TupleDesc + * + * ---------------------------------------------------------------- + */ +TupleDesc +CreateTupleDescCopy(TupleDesc tupdesc) +{ + TupleDesc desc; + int i, size; + + desc = (TupleDesc) palloc(sizeof(struct tupleDesc)); + desc->natts = tupdesc->natts; + size = desc->natts * sizeof (AttributeTupleForm); + desc->attrs = (AttributeTupleForm*) palloc(size); + for (i=0;i<desc->natts;i++) { + desc->attrs[i] = + (AttributeTupleForm)palloc(ATTRIBUTE_TUPLE_SIZE); + memmove(desc->attrs[i], + tupdesc->attrs[i], + ATTRIBUTE_TUPLE_SIZE); + } + return desc; +} + +/* ---------------------------------------------------------------- + * TupleDescInitEntry + * + * This function initializes a single attribute structure in + * a preallocated tuple descriptor. + * ---------------------------------------------------------------- + */ +bool +TupleDescInitEntry(TupleDesc desc, + AttrNumber attributeNumber, + char *attributeName, + char *typeName, + int attdim, + bool attisset) +{ + HeapTuple tuple; + TypeTupleForm typeForm; + AttributeTupleForm att; + + /* ---------------- + * sanity checks + * ---------------- + */ + AssertArg(PointerIsValid(desc)); + AssertArg(attributeNumber >= 1); + /* attributeName's are sometimes NULL, + from resdom's. I don't know why that is, though -- Jolly */ +/* AssertArg(NameIsValid(attributeName));*/ +/* AssertArg(NameIsValid(typeName));*/ + + AssertArg(!PointerIsValid(desc->attrs[attributeNumber - 1])); + + + /* ---------------- + * allocate storage for this attribute + * ---------------- + */ + + att = (AttributeTupleForm) palloc(ATTRIBUTE_TUPLE_SIZE); + desc->attrs[attributeNumber - 1] = att; + + /* ---------------- + * initialize some of the attribute fields + * ---------------- + */ + att->attrelid = 0; /* dummy value */ + + if (attributeName != NULL) + namestrcpy(&(att->attname), attributeName); + else + memset(att->attname.data,0,NAMEDATALEN); + + + att->attdefrel = 0; /* dummy value */ + att->attnvals = 0; /* dummy value */ + att->atttyparg = 0; /* dummy value */ + att->attbound = 0; /* dummy value */ + att->attcanindex = 0; /* dummy value */ + att->attproc = 0; /* dummy value */ + att->attcacheoff = -1; + + att->attnum = attributeNumber; + att->attnelems = attdim; + att->attisset = attisset; + + /* ---------------- + * search the system cache for the type tuple of the attribute + * we are creating so that we can get the typeid and some other + * stuff. + * + * Note: in the special case of + * + * create EMP (name = char16, manager = EMP) + * + * RelationNameCreateHeapRelation() calls BuildDesc() which + * calls this routine and since EMP does not exist yet, the + * system cache lookup below fails. That's fine, but rather + * then doing a elog(WARN) we just leave that information + * uninitialized, return false, then fix things up later. + * -cim 6/14/90 + * ---------------- + */ + tuple = SearchSysCacheTuple(TYPNAME, PointerGetDatum(typeName), + 0,0,0); + if (! HeapTupleIsValid(tuple)) { + /* ---------------- + * here type info does not exist yet so we just fill + * the attribute with dummy information and return false. + * ---------------- + */ + att->atttypid = InvalidOid; + att->attlen = (int16) 0; + att->attbyval = (bool) 0; + att->attalign = 'i'; + return false; + } + + /* ---------------- + * type info exists so we initialize our attribute + * information from the type tuple we found.. + * ---------------- + */ + typeForm = (TypeTupleForm) GETSTRUCT(tuple); + + att->atttypid = tuple->t_oid; + att->attalign = typeForm->typalign; + + /* ------------------------ + If this attribute is a set, what is really stored in the + attribute is the OID of a tuple in the pg_proc catalog. + The pg_proc tuple contains the query string which defines + this set - i.e., the query to run to get the set. + So the atttypid (just assigned above) refers to the type returned + by this query, but the actual length of this attribute is the + length (size) of an OID. + + Why not just make the atttypid point to the OID type, instead + of the type the query returns? Because the executor uses the atttypid + to tell the front end what type will be returned (in BeginCommand), + and in the end the type returned will be the result of the query, not + an OID. + + Why not wait until the return type of the set is known (i.e., the + recursive call to the executor to execute the set has returned) + before telling the front end what the return type will be? Because + the executor is a delicate thing, and making sure that the correct + order of front-end commands is maintained is messy, especially + considering that target lists may change as inherited attributes + are considered, etc. Ugh. + ----------------------------------------- + */ + if (attisset) { + Type t = type("oid"); + att->attlen = tlen(t); + att->attbyval = tbyval(t); + } else { + att->attlen = typeForm->typlen; + att->attbyval = typeForm->typbyval; + } + + + return true; +} + + +/* ---------------------------------------------------------------- + * TupleDescMakeSelfReference + * + * This function initializes a "self-referential" attribute like + * manager in "create EMP (name=text, manager = EMP)". + * It calls TypeShellMake() which inserts a "shell" type + * tuple into pg_type. A self-reference is one kind of set, so + * its size and byval are the same as for a set. See the comments + * above in TupleDescInitEntry. + * ---------------------------------------------------------------- + */ +static void +TupleDescMakeSelfReference(TupleDesc desc, + AttrNumber attnum, + char *relname) +{ + AttributeTupleForm att; + Type t = type("oid"); + + att = desc->attrs[attnum-1]; + att->atttypid = TypeShellMake(relname); + att->attlen = tlen(t); + att->attbyval = tbyval(t); + att->attnelems = 0; +} + +/* ---------------------------------------------------------------- + * BuildDescForRelation + * + * This is a general purpose function identical to BuildDesc + * but is used by the DefineRelation() code to catch the + * special case where you + * + * create FOO ( ..., x = FOO ) + * + * here, the initial type lookup for "x = FOO" will fail + * because FOO isn't in the catalogs yet. But since we + * are creating FOO, instead of doing an elog() we add + * a shell type tuple to pg_type and fix things later + * in amcreate(). + * ---------------------------------------------------------------- + */ +TupleDesc +BuildDescForRelation(List *schema, char *relname) +{ + int natts; + AttrNumber attnum; + List *p; + TupleDesc desc; + char *attname; + char *typename; + int attdim; + bool attisset; + + /* ---------------- + * allocate a new tuple descriptor + * ---------------- + */ + natts = length(schema); + desc = CreateTemplateTupleDesc(natts); + + attnum = 0; + + typename = palloc(NAMEDATALEN+1); + + foreach(p, schema) { + ColumnDef *entry; + List *arry; + + /* ---------------- + * for each entry in the list, get the name and type + * information from the list and have TupleDescInitEntry + * fill in the attribute information we need. + * ---------------- + */ + attnum++; + + entry = lfirst(p); + attname = entry->colname; + arry = entry->typename->arrayBounds; + attisset = entry->typename->setof; + + if (arry != NIL) { + char buf[20]; + + attdim = length(arry); + + /* array of XXX is _XXX (inherited from release 3) */ + sprintf(buf, "_%.*s", NAMEDATALEN, entry->typename->name); + strcpy(typename, buf); + } else { + strcpy(typename, entry->typename->name); + attdim = 0; + } + + if (! TupleDescInitEntry(desc, attnum, attname, + typename, attdim, attisset)) { + /* ---------------- + * if TupleDescInitEntry() fails, it means there is + * no type in the system catalogs. So now we check if + * the type name equals the relation name. If so we + * have a self reference, otherwise it's an error. + * ---------------- + */ + if (!strcmp(typename, relname)) { + TupleDescMakeSelfReference(desc, attnum, relname); + } else + elog(WARN, "DefineRelation: no such type %.*s", + NAMEDATALEN, typename); + } + + /* + * this is for char() and varchar(). When an entry is of type + * char() or varchar(), typlen is set to the appropriate length, + * which we'll use here instead. (The catalog lookup only returns + * the length of bpchar and varchar which is not what we want!) + * - ay 6/95 + */ + if (entry->typename->typlen > 0) { + desc->attrs[attnum - 1]->attlen = entry->typename->typlen; + } + } + return desc; +} + |