analyze.c

关系型数据库 Postgresql 6.5.2

 *	so that the generated names are easily predictable by a person.
 */
static char *
makeObjectName(char *name1, char *name2, char *typename)
{
	char	   *name;
	int			overhead = 0;	/* chars needed for type and underscores */
	int			availchars;		/* chars available for name(s) */
	int			name1chars;		/* chars allocated to name1 */
	int			name2chars;		/* chars allocated to name2 */
	int			ndx;

	name1chars = strlen(name1);
	if (name2)
	{
		name2chars = strlen(name2);
		overhead++;				/* allow for separating underscore */
	}
	else
		name2chars = 0;
	if (typename)
		overhead += strlen(typename) + 1;

	availchars = NAMEDATALEN-1 - overhead;

	/* If we must truncate,  preferentially truncate the longer name.
	 * This logic could be expressed without a loop, but it's simple and
	 * obvious as a loop.
	 */
	while (name1chars + name2chars > availchars)
	{
		if (name1chars > name2chars)
			name1chars--;
		else
			name2chars--;
	}

	/* Now construct the string using the chosen lengths */
	name = palloc(name1chars + name2chars + overhead + 1);
	strncpy(name, name1, name1chars);
	ndx = name1chars;
	if (name2)
	{
		name[ndx++] = '_';
		strncpy(name+ndx, name2, name2chars);
		ndx += name2chars;
	}
	if (typename)
	{
		name[ndx++] = '_';
		strcpy(name+ndx, typename);
	}
	else
		name[ndx] = '\0';

	return name;
}

static char *
CreateIndexName(char *table_name, char *column_name, char *label, List *indices)
{
	int			pass = 0;
	char	   *iname = NULL;
	List	   *ilist;
	char		typename[NAMEDATALEN];

	/* The type name for makeObjectName is label, or labelN if that's
	 * necessary to prevent collisions among multiple indexes for the same
	 * table.  Note there is no check for collisions with already-existing
	 * indexes; this ought to be rethought someday.
	 */
	strcpy(typename, label);

	for (;;)
	{
		iname = makeObjectName(table_name, column_name, typename);

		foreach(ilist, indices)
		{
			IndexStmt  *index = lfirst(ilist);
			if (strcasecmp(iname, index->idxname) == 0)
				break;
		}
		/* ran through entire list? then no name conflict found so done */
		if (ilist == NIL)
			break;

		/* the last one conflicted, so try a new name component */
		pfree(iname);
		sprintf(typename, "%s%d", label, ++pass);
	}

	return iname;
}

/*
 * transformCreateStmt -
 *	  transforms the "create table" statement
 *	  SQL92 allows constraints to be scattered all over, so thumb through
 *	   the columns and collect all constraints into one place.
 *	  If there are any implied indices (e.g. UNIQUE or PRIMARY KEY)
 *	   then expand those into multiple IndexStmt blocks.
 *	  - thomas 1997-12-02
 */
static Query *
transformCreateStmt(ParseState *pstate, CreateStmt *stmt)
{
	Query	   *q;
	List	   *elements;
	Node	   *element;
	List	   *columns;
	List	   *dlist;
	ColumnDef  *column;
	List	   *constraints,
			   *clist;
	Constraint *constraint;
	List	   *keys;
	Ident	   *key;
	List	   *blist = NIL;	/* "before list" of things to do before
								 * creating the table */
	List	   *ilist = NIL;	/* "index list" of things to do after
								 * creating the table */
	IndexStmt  *index,
			   *pkey = NULL;
	IndexElem  *iparam;

	q = makeNode(Query);
	q->commandType = CMD_UTILITY;

	elements = stmt->tableElts;
	constraints = stmt->constraints;
	columns = NIL;
	dlist = NIL;

	/*
	 * Run through each primary element in the table creation clause
	 */
	while (elements != NIL)
	{
		element = lfirst(elements);
		switch (nodeTag(element))
		{
			case T_ColumnDef:
				column = (ColumnDef *) element;
				columns = lappend(columns, column);

				/* Special case SERIAL type? */
				if (column->is_sequence)
				{
					char	   *sname;
					char	   *cstring;
					CreateSeqStmt *sequence;

					sname = makeObjectName(stmt->relname, column->colname,
										   "seq");
					constraint = makeNode(Constraint);
					constraint->contype = CONSTR_DEFAULT;
					constraint->name = sname;
					cstring = palloc(10 + strlen(constraint->name) + 3 + 1);
					strcpy(cstring, "nextval('\"");
					strcat(cstring, constraint->name);
					strcat(cstring, "\"')");
					constraint->def = cstring;
					constraint->keys = NULL;

					column->constraints = lappend(column->constraints, constraint);

					constraint = makeNode(Constraint);
					constraint->contype = CONSTR_UNIQUE;
					constraint->name = makeObjectName(stmt->relname,
													  column->colname,
													  "key");
					column->constraints = lappend(column->constraints, constraint);

					sequence = makeNode(CreateSeqStmt);
					sequence->seqname = pstrdup(sname);
					sequence->options = NIL;

					elog(NOTICE, "CREATE TABLE will create implicit sequence '%s' for SERIAL column '%s.%s'",
					  sequence->seqname, stmt->relname, column->colname);

					blist = lcons(sequence, NIL);
				}

				/* Check for column constraints, if any... */
				if (column->constraints != NIL)
				{
					clist = column->constraints;
					while (clist != NIL)
					{
						constraint = lfirst(clist);
						switch (constraint->contype)
						{
							case CONSTR_NULL:

								/*
								 * We should mark this explicitly, so we
								 * can tell if NULL and NOT NULL are both
								 * specified
								 */
								if (column->is_not_null)
									elog(ERROR, "CREATE TABLE/(NOT) NULL conflicting declaration"
										 " for '%s.%s'", stmt->relname, column->colname);
								column->is_not_null = FALSE;
								break;

							case CONSTR_NOTNULL:
								if (column->is_not_null)
									elog(ERROR, "CREATE TABLE/NOT NULL already specified"
										 " for '%s.%s'", stmt->relname, column->colname);
								column->is_not_null = TRUE;
								break;

							case CONSTR_DEFAULT:
								if (column->defval != NULL)
									elog(ERROR, "CREATE TABLE/DEFAULT multiple values specified"
										 " for '%s.%s'", stmt->relname, column->colname);
								column->defval = constraint->def;
								break;

							case CONSTR_PRIMARY:
								if (constraint->name == NULL)
									constraint->name = makeObjectName(stmt->relname, NULL, "pkey");
								if (constraint->keys == NIL)
									constraint->keys = lappend(constraint->keys, column);
								dlist = lappend(dlist, constraint);
								break;

							case CONSTR_UNIQUE:
								if (constraint->name == NULL)
									constraint->name = makeObjectName(stmt->relname, column->colname, "key");
								if (constraint->keys == NIL)
									constraint->keys = lappend(constraint->keys, column);
								dlist = lappend(dlist, constraint);
								break;

							case CONSTR_CHECK:
								constraints = lappend(constraints, constraint);
								if (constraint->name == NULL)
									constraint->name = makeObjectName(stmt->relname, column->colname, NULL);
								break;

							default:
								elog(ERROR, "parser: unrecognized constraint (internal error)", NULL);
								break;
						}
						clist = lnext(clist);
					}
				}
				break;

			case T_Constraint:
				constraint = (Constraint *) element;
				switch (constraint->contype)
				{
					case CONSTR_PRIMARY:
						if (constraint->name == NULL)
							constraint->name = makeObjectName(stmt->relname, NULL, "pkey");
						dlist = lappend(dlist, constraint);
						break;

					case CONSTR_UNIQUE:
						dlist = lappend(dlist, constraint);
						break;

					case CONSTR_CHECK:
						constraints = lappend(constraints, constraint);
						break;

					case CONSTR_NOTNULL:
					case CONSTR_DEFAULT:
						elog(ERROR, "parser: illegal context for constraint (internal error)", NULL);
						break;
					default:
						elog(ERROR, "parser: unrecognized constraint (internal error)", NULL);
						break;
				}
				break;

			default:
				elog(ERROR, "parser: unrecognized node (internal error)", NULL);
		}

		elements = lnext(elements);
	}

	stmt->tableElts = columns;
	stmt->constraints = constraints;

/* Now run through the "deferred list" to complete the query transformation.
 * For PRIMARY KEYs, mark each column as NOT NULL and create an index.
 * For UNIQUE, create an index as for PRIMARY KEYS, but do not insist on NOT NULL.
 *
 * Note that this code does not currently look for all possible redundant cases
 *	and either ignore or stop with warning. The create might fail later when
 *	names for indices turn out to be duplicated, or a user might have specified
 *	extra useless indices which might hurt performance. - thomas 1997-12-08
 */
	while (dlist != NIL)
	{
		constraint = lfirst(dlist);
		Assert(nodeTag(constraint) == T_Constraint);
		Assert((constraint->contype == CONSTR_PRIMARY)
			   || (constraint->contype == CONSTR_UNIQUE));

		index = makeNode(IndexStmt);

		index->unique = TRUE;
		index->primary = (constraint->contype == CONSTR_PRIMARY ? TRUE : FALSE);
		if (index->primary)
		{
			if (pkey != NULL)
				elog(ERROR, "CREATE TABLE/PRIMARY KEY multiple primary keys"
					 " for table '%s' are not allowed", stmt->relname);
			pkey = (IndexStmt *) index;
		}

		if (constraint->name != NULL)
			index->idxname = pstrdup(constraint->name);
		else if (constraint->contype == CONSTR_PRIMARY)
			index->idxname = makeObjectName(stmt->relname, NULL, "pkey");
		else
			index->idxname = NULL;

		index->relname = stmt->relname;
		index->accessMethod = "btree";
		index->indexParams = NIL;
		index->withClause = NIL;
		index->whereClause = NULL;

		keys = constraint->keys;
		while (keys != NIL)
		{
			key = lfirst(keys);
			columns = stmt->tableElts;
			column = NULL;
			while (columns != NIL)
			{
				column = lfirst(columns);
				if (strcasecmp(column->colname, key->name) == 0)
					break;
				else
					column = NULL;
				columns = lnext(columns);
			}
			if (column == NULL)
				elog(ERROR, "CREATE TABLE column '%s' in key does not exist", key->name);

			if (constraint->contype == CONSTR_PRIMARY)
				column->is_not_null = TRUE;
			iparam = makeNode(IndexElem);
			iparam->name = pstrdup(column->colname);
			iparam->args = NIL;
			iparam->class = NULL;
			iparam->typename = NULL;
			index->indexParams = lappend(index->indexParams, iparam);

			if (index->idxname == NULL)
				index->idxname = CreateIndexName(stmt->relname, iparam->name, "key", ilist);

			keys = lnext(keys);
		}

		if (index->idxname == NULL)	/* should not happen */
			elog(ERROR, "CREATE TABLE: failed to make implicit index name");

		ilist = lappend(ilist, index);
		dlist = lnext(dlist);
	}

/* OK, now finally, if there is a primary key, then make sure that there aren't any redundant
 * unique indices defined on columns. This can arise if someone specifies UNIQUE explicitly
 * or if a SERIAL column was defined along with a table PRIMARY KEY constraint.
 * - thomas 1999-05-11
 */
	if (pkey != NULL)
	{
		dlist = ilist;
		ilist = NIL;
		while (dlist != NIL)
		{
			List *pcols, *icols;
			int plen, ilen;
			int	keep = TRUE;

			index = lfirst(dlist);
			pcols = pkey->indexParams;
			icols = index->indexParams;

			plen = length(pcols);
			ilen = length(icols);

			/* Not the same as the primary key? Then we should look... */
			if ((index != pkey) && (ilen == plen))
			{
				keep = FALSE;
				while ((pcols != NIL) && (icols != NIL))
				{
					IndexElem *pcol = lfirst(pcols);
					IndexElem *icol = lfirst(icols);
					char *pname = pcol->name;
					char *iname = icol->name;

					/* different names? then no match... */
					if (strcmp(iname, pname) != 0)
					{
						keep = TRUE;
						break;
					}
					pcols = lnext(pcols);
					icols = lnext(icols);
				}
			}

			if (keep)
				ilist = lappend(ilist, index);
			dlist = lnext(dlist);
		}
	}

	dlist = ilist;
	while (dlist != NIL)
	{
		index = lfirst(dlist);
		elog(NOTICE, "CREATE TABLE/%s will create implicit index '%s' for table '%s'",
			 (index->primary ? "PRIMARY KEY" : "UNIQUE"),
			 index->idxname, stmt->relname);
		dlist = lnext(dlist);
	}

	q->utilityStmt = (Node *) stmt;