src/backend/access/common/tupdesc.c

/*-------------------------------------------------------------------------
 *
 * tupdesc.c
 *	  POSTGRES tuple descriptor support code
 *
 * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $PostgreSQL: pgsql/src/backend/access/common/tupdesc.c,v 1.126 2009/06/11 14:48:53 momjian Exp $
 *
 * NOTES
 *	  some of the executor utility code such as "ExecTypeFromTL" should be
 *	  moved here.
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include "catalog/catquery.h"
#include "catalog/pg_type.h"
#include "parser/parse_type.h"
#include "utils/builtins.h"
#include "utils/resowner.h"
#include "utils/syscache.h"


/*
 * CreateTemplateTupleDesc
 *		This function allocates an empty tuple descriptor structure.
 *
 * Tuple type ID information is initially set for an anonymous record type;
 * caller can overwrite this if needed.
 */
TupleDesc
CreateTemplateTupleDesc(int natts, bool hasoid)
{
	TupleDesc	desc;
	char	   *stg;
	int			attroffset;

	/*
	 * sanity checks
	 */
	AssertArg(natts >= 0);

	/*
	 * Allocate enough memory for the tuple descriptor, including the
	 * attribute rows, and set up the attribute row pointers.
	 *
	 * Note: we assume that sizeof(struct tupleDesc) is a multiple of the
	 * struct pointer alignment requirement, and hence we don't need to insert
	 * alignment padding between the struct and the array of attribute row
	 * pointers.
	 *
	 * Note: Only the fixed part of pg_attribute rows is included in tuple
	 * descriptors, so we only need ATTRIBUTE_FIXED_PART_SIZE space per attr.
	 * That might need alignment padding, however.
	 */
	attroffset = sizeof(struct tupleDesc) + natts * sizeof(Form_pg_attribute);
	attroffset = MAXALIGN(attroffset);
	stg = palloc(attroffset + natts * MAXALIGN(ATTRIBUTE_FIXED_PART_SIZE));
	desc = (TupleDesc) stg;

	if (natts > 0)
	{
		Form_pg_attribute *attrs;
		int			i;

		attrs = (Form_pg_attribute *) (stg + sizeof(struct tupleDesc));
		desc->attrs = attrs;
		stg += attroffset;
		for (i = 0; i < natts; i++)
		{
			attrs[i] = (Form_pg_attribute) stg;
			stg += MAXALIGN(ATTRIBUTE_FIXED_PART_SIZE);
		}
	}
	else
		desc->attrs = NULL;

	/*
	 * Initialize other fields of the tupdesc.
	 */
	desc->natts = natts;
	desc->constr = NULL;
	desc->tdtypeid = RECORDOID;
	desc->tdtypmod = -1;
	desc->tdhasoid = hasoid;
	desc->tdrefcount = -1;		/* assume not reference-counted */

	return desc;
}

/*
 * CreateTupleDesc
 *		This function allocates a new TupleDesc pointing to a given
 *		Form_pg_attribute array.
 *
 * Note: if the TupleDesc is ever freed, the Form_pg_attribute array
 * will not be freed thereby.
 *
 * Tuple type ID information is initially set for an anonymous record type;
 * caller can overwrite this if needed.
 */
TupleDesc
CreateTupleDesc(int natts, bool hasoid, Form_pg_attribute *attrs)
{
	TupleDesc	desc;

	/*
	 * sanity checks
	 */
	AssertArg(natts >= 0);

	desc = (TupleDesc) palloc(sizeof(struct tupleDesc));
	desc->attrs = attrs;
	desc->natts = natts;
	desc->constr = NULL;
	desc->tdtypeid = RECORDOID;
	desc->tdtypmod = -1;
	desc->tdhasoid = hasoid;
	desc->tdrefcount = -1;		/* assume not reference-counted */

	return desc;
}

/*
 * CreateTupleDescCopy
 *		This function creates a new TupleDesc by copying from an existing
 *		TupleDesc.
 *
 * !!! Constraints and defaults are not copied !!!
 */
TupleDesc
CreateTupleDescCopy(TupleDesc tupdesc)
{
	TupleDesc	desc;
	int			i;

	desc = CreateTemplateTupleDesc(tupdesc->natts, tupdesc->tdhasoid);

	for (i = 0; i < desc->natts; i++)
	{
		memcpy(desc->attrs[i], tupdesc->attrs[i], ATTRIBUTE_FIXED_PART_SIZE);
		desc->attrs[i]->attnotnull = false;
		desc->attrs[i]->atthasdef = false;
	}

	desc->tdtypeid = tupdesc->tdtypeid;
	desc->tdtypmod = tupdesc->tdtypmod;

	return desc;
}

/*
 * CreateTupleDescCopyConstr
 *		This function creates a new TupleDesc by copying from an existing
 *		TupleDesc (including its constraints and defaults).
 */
TupleDesc
CreateTupleDescCopyConstr(TupleDesc tupdesc)
{
	TupleDesc	desc;
	TupleConstr *constr = tupdesc->constr;
	int			i;

	desc = CreateTemplateTupleDesc(tupdesc->natts, tupdesc->tdhasoid);

	for (i = 0; i < desc->natts; i++)
	{
		memcpy(desc->attrs[i], tupdesc->attrs[i], ATTRIBUTE_FIXED_PART_SIZE);
	}

	if (constr)
	{
		TupleConstr *cpy = (TupleConstr *) palloc0(sizeof(TupleConstr));

		cpy->has_not_null = constr->has_not_null;

		if ((cpy->num_defval = constr->num_defval) > 0)
		{
			cpy->defval = (AttrDefault *) palloc(cpy->num_defval * sizeof(AttrDefault));
			memcpy(cpy->defval, constr->defval, cpy->num_defval * sizeof(AttrDefault));
			for (i = cpy->num_defval - 1; i >= 0; i--)
			{
				if (constr->defval[i].adbin)
					cpy->defval[i].adbin = pstrdup(constr->defval[i].adbin);
			}
		}

		if ((cpy->num_check = constr->num_check) > 0)
		{
			cpy->check = (ConstrCheck *) palloc(cpy->num_check * sizeof(ConstrCheck));
			memcpy(cpy->check, constr->check, cpy->num_check * sizeof(ConstrCheck));
			for (i = cpy->num_check - 1; i >= 0; i--)
			{
				if (constr->check[i].ccname)
					cpy->check[i].ccname = pstrdup(constr->check[i].ccname);
				if (constr->check[i].ccbin)
					cpy->check[i].ccbin = pstrdup(constr->check[i].ccbin);
			}
		}

		desc->constr = cpy;
	}

	desc->tdtypeid = tupdesc->tdtypeid;
	desc->tdtypmod = tupdesc->tdtypmod;

	return desc;
}

/*
 * Free a TupleDesc including all substructure
 */
void
FreeTupleDesc(TupleDesc tupdesc)
{
	int			i;

	/*
	 * Possibly this should assert tdrefcount == 0, to disallow explicit
	 * freeing of un-refcounted tupdescs?
	 */
	Assert(tupdesc->tdrefcount <= 0);

	if (tupdesc->constr)
	{
		if (tupdesc->constr->num_defval > 0)
		{
			AttrDefault *attrdef = tupdesc->constr->defval;

			for (i = tupdesc->constr->num_defval - 1; i >= 0; i--)
			{
				if (attrdef[i].adbin)
					pfree(attrdef[i].adbin);
			}
			pfree(attrdef);
		}
		if (tupdesc->constr->num_check > 0)
		{
			ConstrCheck *check = tupdesc->constr->check;

			for (i = tupdesc->constr->num_check - 1; i >= 0; i--)
			{
				if (check[i].ccname)
					pfree(check[i].ccname);
				if (check[i].ccbin)
					pfree(check[i].ccbin);
			}
			pfree(check);
		}
		pfree(tupdesc->constr);
	}

	pfree(tupdesc);
}

/*
 * Increment the reference count of a tupdesc, and log the reference in
 * CurrentResourceOwner.
 *
 * Do not apply this to tupdescs that are not being refcounted.  (Use the
 * macro PinTupleDesc for tupdescs of uncertain status.)
 */
void
IncrTupleDescRefCount(TupleDesc tupdesc)
{
	Assert(tupdesc->tdrefcount >= 0);

	ResourceOwnerEnlargeTupleDescs(CurrentResourceOwner);
	tupdesc->tdrefcount++;
	ResourceOwnerRememberTupleDesc(CurrentResourceOwner, tupdesc);
}

/*
 * Decrement the reference count of a tupdesc, remove the corresponding
 * reference from CurrentResourceOwner, and free the tupdesc if no more
 * references remain.
 *
 * Do not apply this to tupdescs that are not being refcounted.  (Use the
 * macro ReleaseTupleDesc for tupdescs of uncertain status.)
 */
void
DecrTupleDescRefCount(TupleDesc tupdesc)
{
	Assert(tupdesc->tdrefcount > 0);

	ResourceOwnerForgetTupleDesc(CurrentResourceOwner, tupdesc);
	if (--tupdesc->tdrefcount == 0)
		FreeTupleDesc(tupdesc);
}

/*
 * Compare two TupleDesc structures for logical equality
 *
 * Note: we deliberately do not check the attrelid and tdtypmod fields.
 * This allows typcache.c to use this routine to see if a cached record type
 * matches a requested type, and is harmless for relcache.c's uses.
 * We don't compare tdrefcount, either.
 */
bool
equalTupleDescs(TupleDesc tupdesc1, TupleDesc tupdesc2, bool strict)
{
	int			i,
				j,
				n;

	if (tupdesc1->natts != tupdesc2->natts)
		return false;
	if (strict && tupdesc1->tdtypeid != tupdesc2->tdtypeid)
		return false;
	if (tupdesc1->tdhasoid != tupdesc2->tdhasoid)
		return false;

	for (i = 0; i < tupdesc1->natts; i++)
	{
		Form_pg_attribute attr1 = tupdesc1->attrs[i];
		Form_pg_attribute attr2 = tupdesc2->attrs[i];

		/*
		 * We do not need to check every single field here: we can disregard
		 * attrelid and attnum (which were used to place the row in the attrs
		 * array in the first place).  It might look like we could dispense
		 * with checking attlen/attbyval/attalign, since these are derived
		 * from atttypid; but in the case of dropped columns we must check
		 * them (since atttypid will be zero for all dropped columns) and in
		 * general it seems safer to check them always.
		 *
		 * attcacheoff must NOT be checked since it's possibly not set in both
		 * copies.
		 */
		if (strcmp(NameStr(attr1->attname), NameStr(attr2->attname)) != 0)
			return false;
		if (attr1->atttypid != attr2->atttypid)
			return false;
		if (attr1->attstattarget != attr2->attstattarget)
			return false;
		if (attr1->attlen != attr2->attlen)
			return false;
		if (attr1->attndims != attr2->attndims)
			return false;
		if (attr1->atttypmod != attr2->atttypmod)
			return false;
		if (attr1->attbyval != attr2->attbyval)
			return false;
		if (attr1->attstorage != attr2->attstorage)
			return false;
		if (attr1->attalign != attr2->attalign)
			return false;

        if (strict)
        {
            if (attr1->attnotnull != attr2->attnotnull)
                return false;
            if (attr1->atthasdef != attr2->atthasdef)
                return false;
            if (attr1->attisdropped != attr2->attisdropped)
                return false;
            if (attr1->attislocal != attr2->attislocal)
                return false;
            if (attr1->attinhcount != attr2->attinhcount)
                return false;
        }
	}

    if (!strict) 
        return true;

	if (tupdesc1->constr != NULL)
	{
		TupleConstr *constr1 = tupdesc1->constr;
		TupleConstr *constr2 = tupdesc2->constr;

		if (constr2 == NULL)
			return false;
		if (constr1->has_not_null != constr2->has_not_null)
			return false;
		n = constr1->num_defval;
		if (n != (int) constr2->num_defval)
			return false;
		for (i = 0; i < n; i++)
		{
			AttrDefault *defval1 = constr1->defval + i;
			AttrDefault *defval2 = constr2->defval;

			/*
			 * We can't assume that the items are always read from the system
			 * catalogs in the same order; so use the adnum field to identify
			 * the matching item to compare.
			 */
			for (j = 0; j < n; defval2++, j++)
			{
				if (defval1->adnum == defval2->adnum)
					break;
			}
			if (j >= n)
				return false;
			if (strcmp(defval1->adbin, defval2->adbin) != 0)
				return false;
		}
		n = constr1->num_check;
		if (n != (int) constr2->num_check)
			return false;
		for (i = 0; i < n; i++)
		{
			ConstrCheck *check1 = constr1->check + i;
			ConstrCheck *check2 = constr2->check;

			/*
			 * Similarly, don't assume that the checks are always read in the
			 * same order; match them up by name and contents. (The name
			 * *should* be unique, but...)
			 */
			for (j = 0; j < n; check2++, j++)
			{
				if (strcmp(check1->ccname, check2->ccname) == 0 &&
					strcmp(check1->ccbin, check2->ccbin) == 0)
					break;
			}
			if (j >= n)
				return false;
		}
	}
	else if (tupdesc2->constr != NULL)
		return false;
	return true;
}

/*
 * TupleDescInitEntry
 *		This function initializes a single attribute structure in
 *		a previously allocated tuple descriptor.
 *
 * If attributeName is NULL, the attname field is set to an empty string
 * (this is for cases where we don't know or need a name for the field).
 * Also, some callers use this function to change the datatype-related fields
 * in an existing tupdesc; they pass attributeName = NameStr(att->attname)
 * to indicate that the attname field shouldn't be modified.
 */
void
TupleDescInitEntry(TupleDesc desc,
				   AttrNumber attributeNumber,
				   const char *attributeName,
				   Oid oidtypeid,
				   int32 typmod,
				   int attdim)
{
	HeapTuple	tuple;
	Form_pg_type typeForm;
	Form_pg_attribute att;
	cqContext	*pcqCtx;

	/*
	 * sanity checks
	 */
	AssertArg(PointerIsValid(desc));
	AssertArg(attributeNumber >= 1);
	AssertArg(attributeNumber <= desc->natts);

	/*
	 * initialize the attribute fields
	 */
	att = desc->attrs[attributeNumber - 1];

	att->attrelid = 0;			/* dummy value */

	/*
	 * Note: attributeName can be NULL, because the planner doesn't always
	 * fill in valid resname values in targetlists, particularly for resjunk
	 * attributes. Also, do nothing if caller wants to re-use the old attname.
	 */
	if (attributeName == NULL)
		MemSet(NameStr(att->attname), 0, NAMEDATALEN);
	else if (attributeName != NameStr(att->attname))
		namestrcpy(&(att->attname), attributeName);

	att->attstattarget = -1;
	att->attcacheoff = -1;
	att->atttypmod = typmod;

	att->attnum = attributeNumber;
	att->attndims = attdim;

	att->attnotnull = false;
	att->atthasdef = false;
	att->attisdropped = false;
	att->attislocal = true;
	att->attinhcount = 0;

	pcqCtx = caql_beginscan(
			NULL,
			cql("SELECT * FROM pg_type "
				" WHERE oid = :1 ",
				ObjectIdGetDatum(oidtypeid)));

	tuple = caql_getnext(pcqCtx);

	if (!HeapTupleIsValid(tuple))
		elog(ERROR, "cache lookup failed for type %u", oidtypeid);
	typeForm = (Form_pg_type) GETSTRUCT(tuple);

	att->atttypid = oidtypeid;
	att->attlen = typeForm->typlen;
	att->attbyval = typeForm->typbyval;
	att->attalign = typeForm->typalign;
	att->attstorage = typeForm->typstorage;

	caql_endscan(pcqCtx);
}


/*
 * BuildDescForRelation
 *
 * Given a relation schema (list of ColumnDef nodes), build a TupleDesc.
 *
 * Note: the default assumption is no OIDs; caller may modify the returned
 * TupleDesc if it wants OIDs.	Also, tdtypeid will need to be filled in
 * later on.
 */
TupleDesc
BuildDescForRelation(List *schema)
{
	int			natts;
	AttrNumber	attnum;
	ListCell   *l;
	TupleDesc	desc;
	AttrDefault *attrdef = NULL;
	TupleConstr *constr = (TupleConstr *) palloc0(sizeof(TupleConstr));
	char	   *attname;
	int32		atttypmod;
	int			attdim;
	int			ndef = 0;

	/*
	 * allocate a new tuple descriptor
	 */
	natts = list_length(schema);
	desc = CreateTemplateTupleDesc(natts, false);
	constr->has_not_null = false;

	attnum = 0;

	foreach(l, schema)
	{
		ColumnDef  *entry = lfirst(l);

		/*
		 * 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++;

		attname = entry->colname;
		atttypmod = entry->typname->typmod;
		attdim = list_length(entry->typname->arrayBounds);

		if (entry->typname->setof)
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
					 errmsg("column \"%s\" cannot be declared SETOF",
							attname)));

		TupleDescInitEntry(desc, attnum, attname,
						   typenameTypeId(NULL, entry->typname),
						   atttypmod, attdim);

		/* Fill in additional stuff not handled by TupleDescInitEntry */
		if (entry->is_not_null)
			constr->has_not_null = true;
		desc->attrs[attnum - 1]->attnotnull = entry->is_not_null;

		/*
		 * Note we copy only pre-cooked default expressions. Digestion of raw
		 * ones is someone else's problem.
		 */
		if (entry->cooked_default != NULL)
		{
			if (attrdef == NULL)
				attrdef = (AttrDefault *) palloc(natts * sizeof(AttrDefault));
			attrdef[ndef].adnum = attnum;
			attrdef[ndef].adbin = pstrdup(entry->cooked_default);
			ndef++;
			desc->attrs[attnum - 1]->atthasdef = true;
		}

		desc->attrs[attnum - 1]->attislocal = entry->is_local;
		desc->attrs[attnum - 1]->attinhcount = entry->inhcount;
	}

	if (constr->has_not_null || ndef > 0)
	{
		desc->constr = constr;

		if (ndef > 0)			/* DEFAULTs */
		{
			if (ndef < natts)
				constr->defval = (AttrDefault *)
					repalloc(attrdef, ndef * sizeof(AttrDefault));
			else
				constr->defval = attrdef;
			constr->num_defval = ndef;
		}
		else
		{
			constr->defval = NULL;
			constr->num_defval = 0;
		}
		constr->check = NULL;
		constr->num_check = 0;
	}
	else
	{
		pfree(constr);
		desc->constr = NULL;
	}

	return desc;
}

/*
 * BuildDescFromLists
 *
 * Build a TupleDesc given lists of column names (as String nodes),
 * column type OIDs, and column typmods.  No constraints are generated.
 *
 * This is essentially a cut-down version of BuildDescForRelation for use
 * with functions returning RECORD.
 */
TupleDesc
BuildDescFromLists(List *names, List *types, List *typmods)
{
	int			natts;
	AttrNumber	attnum;
	ListCell   *l1;
	ListCell   *l2;
	ListCell   *l3;
	TupleDesc	desc;

	natts = list_length(names);
	Assert(natts == list_length(types));
	Assert(natts == list_length(typmods));

	/*
	 * allocate a new tuple descriptor
	 */
	desc = CreateTemplateTupleDesc(natts, false);

	attnum = 0;

	l2 = list_head(types);
	l3 = list_head(typmods);
	foreach(l1, names)
	{
		char	   *attname = strVal(lfirst(l1));
		Oid			atttypid;
		int32		atttypmod;

		atttypid = lfirst_oid(l2);
		l2 = lnext(l2);
		atttypmod = lfirst_int(l3);
		l3 = lnext(l3);

		attnum++;

		TupleDescInitEntry(desc, attnum, attname, atttypid, atttypmod, 0);
	}

	return desc;
}