diff options
Diffstat (limited to 'src/backend/commands/indexcmds.c')
| -rw-r--r-- | src/backend/commands/indexcmds.c | 148 |
1 files changed, 121 insertions, 27 deletions
diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c index 1fe8e58e585..d141c83c1bf 100644 --- a/src/backend/commands/indexcmds.c +++ b/src/backend/commands/indexcmds.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/commands/indexcmds.c,v 1.120 2004/05/26 04:41:11 neilc Exp $ + * $PostgreSQL: pgsql/src/backend/commands/indexcmds.c,v 1.121 2004/06/10 17:55:56 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -28,10 +28,10 @@ #include "commands/defrem.h" #include "commands/tablecmds.h" #include "executor/executor.h" +#include "mb/pg_wchar.h" #include "miscadmin.h" #include "optimizer/clauses.h" #include "optimizer/prep.h" -#include "parser/analyze.h" #include "parser/parsetree.h" #include "parser/parse_coerce.h" #include "parser/parse_expr.h" @@ -53,8 +53,6 @@ static void ComputeIndexAttrs(IndexInfo *indexInfo, Oid *classOidP, static Oid GetIndexOpClass(List *opclass, Oid attrType, char *accessMethodName, Oid accessMethodId); static Oid GetDefaultOpClass(Oid attrType, Oid accessMethodId); -static char *CreateIndexName(const char *table_name, const char *column_name, - const char *label, Oid inamespace); static bool relationHasPrimaryKey(Relation rel); @@ -159,18 +157,18 @@ DefineIndex(RangeVar *heapRelation, if (indexRelationName == NULL) { if (primary) - indexRelationName = CreateIndexName(RelationGetRelationName(rel), - NULL, - "pkey", - namespaceId); + indexRelationName = ChooseRelationName(RelationGetRelationName(rel), + NULL, + "pkey", + namespaceId); else { IndexElem *iparam = (IndexElem *) linitial(attributeList); - indexRelationName = CreateIndexName(RelationGetRelationName(rel), - iparam->name, - "key", - namespaceId); + indexRelationName = ChooseRelationName(RelationGetRelationName(rel), + iparam->name, + "key", + namespaceId); } } @@ -657,35 +655,131 @@ GetDefaultOpClass(Oid attrType, Oid accessMethodId) } /* - * Select a nonconflicting name for an index. + * makeObjectName() + * + * Create a name for an implicitly created index, sequence, constraint, etc. + * + * The parameters are typically: the original table name, the original field + * name, and a "type" string (such as "seq" or "pkey"). The field name + * and/or type can be NULL if not relevant. + * + * The result is a palloc'd string. + * + * The basic result we want is "name1_name2_label", omitting "_name2" or + * "_label" when those parameters are NULL. However, we must generate + * a name with less than NAMEDATALEN characters! So, we truncate one or + * both names if necessary to make a short-enough string. The label part + * is never truncated (so it had better be reasonably short). + * + * The caller is responsible for checking uniqueness of the generated + * name and retrying as needed; retrying will be done by altering the + * "label" string (which is why we never truncate that part). */ -static char * -CreateIndexName(const char *table_name, const char *column_name, - const char *label, Oid inamespace) +char * +makeObjectName(const char *name1, const char *name2, const char *label) { - int pass = 0; - char *iname = NULL; - char typename[NAMEDATALEN]; + char *name; + int overhead = 0; /* chars needed for label 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 (label) + overhead += strlen(label) + 1; + + availchars = NAMEDATALEN - 1 - overhead; + Assert(availchars > 0); /* else caller chose a bad label */ /* - * The type name for makeObjectName is label, or labelN if that's - * necessary to prevent collision with existing indexes. + * 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. */ - strncpy(typename, label, sizeof(typename)); + while (name1chars + name2chars > availchars) + { + if (name1chars > name2chars) + name1chars--; + else + name2chars--; + } + + if (name1) + name1chars = pg_mbcliplen(name1, name1chars, name1chars); + if (name2) + name2chars = pg_mbcliplen(name2, name2chars, name2chars); + + /* Now construct the string using the chosen lengths */ + name = palloc(name1chars + name2chars + overhead + 1); + memcpy(name, name1, name1chars); + ndx = name1chars; + if (name2) + { + name[ndx++] = '_'; + memcpy(name + ndx, name2, name2chars); + ndx += name2chars; + } + if (label) + { + name[ndx++] = '_'; + strcpy(name + ndx, label); + } + else + name[ndx] = '\0'; + + return name; +} + +/* + * Select a nonconflicting name for a new relation. This is ordinarily + * used to choose index names (which is why it's here) but it can also + * be used for sequences, or any autogenerated relation kind. + * + * name1, name2, and label are used the same way as for makeObjectName(), + * except that the label can't be NULL; digits will be appended to the label + * if needed to create a name that is unique within the specified namespace. + * + * Note: it is theoretically possible to get a collision anyway, if someone + * else chooses the same name concurrently. This is fairly unlikely to be + * a problem in practice, especially if one is holding an exclusive lock on + * the relation identified by name1. However, if choosing multiple names + * within a single command, you'd better create the new object and do + * CommandCounterIncrement before choosing the next one! + * + * Returns a palloc'd string. + */ +char * +ChooseRelationName(const char *name1, const char *name2, + const char *label, Oid namespace) +{ + int pass = 0; + char *relname = NULL; + char modlabel[NAMEDATALEN]; + + /* try the unmodified label first */ + StrNCpy(modlabel, label, sizeof(modlabel)); for (;;) { - iname = makeObjectName(table_name, column_name, typename); + relname = makeObjectName(name1, name2, modlabel); - if (!OidIsValid(get_relname_relid(iname, inamespace))) + if (!OidIsValid(get_relname_relid(relname, namespace))) break; /* found a conflict, so try a new name component */ - pfree(iname); - snprintf(typename, sizeof(typename), "%s%d", label, ++pass); + pfree(relname); + snprintf(modlabel, sizeof(modlabel), "%s%d", label, ++pass); } - return iname; + return relname; } /* |