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Identity columns
This is the SQL standard-conforming variant of PostgreSQL's serial columns. It fixes a few usability issues that serial columns have: - CREATE TABLE / LIKE copies default but refers to same sequence - cannot add/drop serialness with ALTER TABLE - dropping default does not drop sequence - need to grant separate privileges to sequence - other slight weirdnesses because serial is some kind of special macro Reviewed-by: Vitaly Burovoy <vitaly.burovoy@gmail.com>
This commit is contained in:
Peter Eisentraut
@ -42,6 +42,7 @@
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#include "catalog/pg_type.h"
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#include "commands/comment.h"
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#include "commands/defrem.h"
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#include "commands/sequence.h"
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#include "commands/tablecmds.h"
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#include "commands/tablespace.h"
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#include "miscadmin.h"
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@ -356,6 +357,132 @@ transformCreateStmt(CreateStmt *stmt, const char *queryString)
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return result;
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}
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static void
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generateSerialExtraStmts(CreateStmtContext *cxt, ColumnDef *column,
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Oid seqtypid, List *seqoptions, bool for_identity,
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char **snamespace_p, char **sname_p)
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{
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ListCell *option;
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DefElem *nameEl = NULL;
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Oid snamespaceid;
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char *snamespace;
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char *sname;
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CreateSeqStmt *seqstmt;
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AlterSeqStmt *altseqstmt;
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List *attnamelist;
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/*
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* Determine namespace and name to use for the sequence.
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*
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* First, check if a sequence name was passed in as an option. This is
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* used by pg_dump. Else, generate a name.
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*
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* Although we use ChooseRelationName, it's not guaranteed that the
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* selected sequence name won't conflict; given sufficiently long
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* field names, two different serial columns in the same table could
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* be assigned the same sequence name, and we'd not notice since we
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* aren't creating the sequence quite yet. In practice this seems
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* quite unlikely to be a problem, especially since few people would
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* need two serial columns in one table.
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*/
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foreach(option, seqoptions)
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{
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DefElem *defel = castNode(DefElem, lfirst(option));
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if (strcmp(defel->defname, "sequence_name") == 0)
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{
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if (nameEl)
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("conflicting or redundant options")));
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nameEl = defel;
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}
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}
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if (nameEl)
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{
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RangeVar *rv = makeRangeVarFromNameList(castNode(List, nameEl->arg));
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snamespace = rv->schemaname;
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sname = rv->relname;
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seqoptions = list_delete_ptr(seqoptions, nameEl);
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}
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else
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{
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if (cxt->rel)
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snamespaceid = RelationGetNamespace(cxt->rel);
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else
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{
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snamespaceid = RangeVarGetCreationNamespace(cxt->relation);
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RangeVarAdjustRelationPersistence(cxt->relation, snamespaceid);
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}
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snamespace = get_namespace_name(snamespaceid);
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sname = ChooseRelationName(cxt->relation->relname,
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column->colname,
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"seq",
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snamespaceid);
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}
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ereport(DEBUG1,
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(errmsg("%s will create implicit sequence \"%s\" for serial column \"%s.%s\"",
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cxt->stmtType, sname,
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cxt->relation->relname, column->colname)));
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/*
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* Build a CREATE SEQUENCE command to create the sequence object, and
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* add it to the list of things to be done before this CREATE/ALTER
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* TABLE.
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*/
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seqstmt = makeNode(CreateSeqStmt);
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seqstmt->for_identity = for_identity;
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seqstmt->sequence = makeRangeVar(snamespace, sname, -1);
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seqstmt->options = seqoptions;
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/*
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* If a sequence data type was specified, add it to the options. Prepend
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* to the list rather than append; in case a user supplied their own AS
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* clause, the "redundant options" error will point to their occurrence,
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* not our synthetic one.
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*/
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if (seqtypid)
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seqstmt->options = lcons(makeDefElem("as", (Node *) makeTypeNameFromOid(seqtypid, -1), -1),
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seqstmt->options);
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/*
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* If this is ALTER ADD COLUMN, make sure the sequence will be owned
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* by the table's owner. The current user might be someone else
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* (perhaps a superuser, or someone who's only a member of the owning
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* role), but the SEQUENCE OWNED BY mechanisms will bleat unless table
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* and sequence have exactly the same owning role.
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*/
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if (cxt->rel)
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seqstmt->ownerId = cxt->rel->rd_rel->relowner;
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else
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seqstmt->ownerId = InvalidOid;
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cxt->blist = lappend(cxt->blist, seqstmt);
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/*
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* Build an ALTER SEQUENCE ... OWNED BY command to mark the sequence
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* as owned by this column, and add it to the list of things to be
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* done after this CREATE/ALTER TABLE.
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*/
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altseqstmt = makeNode(AlterSeqStmt);
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altseqstmt->sequence = makeRangeVar(snamespace, sname, -1);
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attnamelist = list_make3(makeString(snamespace),
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makeString(cxt->relation->relname),
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makeString(column->colname));
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altseqstmt->options = list_make1(makeDefElem("owned_by",
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(Node *) attnamelist, -1));
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altseqstmt->for_identity = for_identity;
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cxt->alist = lappend(cxt->alist, altseqstmt);
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if (snamespace_p)
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*snamespace_p = snamespace;
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if (sname_p)
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*sname_p = sname;
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}
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/*
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* transformColumnDefinition -
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* transform a single ColumnDef within CREATE TABLE
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@ -367,7 +494,7 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
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bool is_serial;
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bool saw_nullable;
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bool saw_default;
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Constraint *constraint;
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bool saw_identity;
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ListCell *clist;
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cxt->columns = lappend(cxt->columns, column);
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@ -422,83 +549,17 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
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/* Special actions for SERIAL pseudo-types */
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if (is_serial)
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{
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Oid snamespaceid;
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char *snamespace;
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char *sname;
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char *qstring;
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A_Const *snamenode;
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TypeCast *castnode;
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FuncCall *funccallnode;
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CreateSeqStmt *seqstmt;
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AlterSeqStmt *altseqstmt;
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List *attnamelist;
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Constraint *constraint;
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/*
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* Determine namespace and name to use for the sequence.
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*
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* Although we use ChooseRelationName, it's not guaranteed that the
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* selected sequence name won't conflict; given sufficiently long
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* field names, two different serial columns in the same table could
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* be assigned the same sequence name, and we'd not notice since we
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* aren't creating the sequence quite yet. In practice this seems
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* quite unlikely to be a problem, especially since few people would
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* need two serial columns in one table.
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*/
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if (cxt->rel)
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snamespaceid = RelationGetNamespace(cxt->rel);
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else
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{
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snamespaceid = RangeVarGetCreationNamespace(cxt->relation);
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RangeVarAdjustRelationPersistence(cxt->relation, snamespaceid);
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}
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snamespace = get_namespace_name(snamespaceid);
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sname = ChooseRelationName(cxt->relation->relname,
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column->colname,
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"seq",
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snamespaceid);
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ereport(DEBUG1,
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(errmsg("%s will create implicit sequence \"%s\" for serial column \"%s.%s\"",
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cxt->stmtType, sname,
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cxt->relation->relname, column->colname)));
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/*
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* Build a CREATE SEQUENCE command to create the sequence object, and
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* add it to the list of things to be done before this CREATE/ALTER
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* TABLE.
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*/
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seqstmt = makeNode(CreateSeqStmt);
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seqstmt->sequence = makeRangeVar(snamespace, sname, -1);
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seqstmt->options = list_make1(makeDefElem("as", (Node *) makeTypeNameFromOid(column->typeName->typeOid, -1), -1));
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/*
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* If this is ALTER ADD COLUMN, make sure the sequence will be owned
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* by the table's owner. The current user might be someone else
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* (perhaps a superuser, or someone who's only a member of the owning
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* role), but the SEQUENCE OWNED BY mechanisms will bleat unless table
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* and sequence have exactly the same owning role.
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*/
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if (cxt->rel)
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seqstmt->ownerId = cxt->rel->rd_rel->relowner;
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else
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seqstmt->ownerId = InvalidOid;
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cxt->blist = lappend(cxt->blist, seqstmt);
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/*
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* Build an ALTER SEQUENCE ... OWNED BY command to mark the sequence
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* as owned by this column, and add it to the list of things to be
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* done after this CREATE/ALTER TABLE.
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*/
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altseqstmt = makeNode(AlterSeqStmt);
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altseqstmt->sequence = makeRangeVar(snamespace, sname, -1);
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attnamelist = list_make3(makeString(snamespace),
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makeString(cxt->relation->relname),
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makeString(column->colname));
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altseqstmt->options = list_make1(makeDefElem("owned_by",
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(Node *) attnamelist, -1));
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cxt->alist = lappend(cxt->alist, altseqstmt);
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generateSerialExtraStmts(cxt, column,
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column->typeName->typeOid, NIL, false,
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&snamespace, &sname);
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/*
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* Create appropriate constraints for SERIAL. We do this in full,
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@ -540,10 +601,11 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
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saw_nullable = false;
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saw_default = false;
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saw_identity = false;
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foreach(clist, column->constraints)
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{
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constraint = castNode(Constraint, lfirst(clist));
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Constraint *constraint = castNode(Constraint, lfirst(clist));
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switch (constraint->contype)
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{
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@ -584,6 +646,33 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
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saw_default = true;
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break;
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case CONSTR_IDENTITY:
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{
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Type ctype;
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Oid typeOid;
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ctype = typenameType(cxt->pstate, column->typeName, NULL);
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typeOid = HeapTupleGetOid(ctype);
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ReleaseSysCache(ctype);
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if (saw_identity)
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("multiple identity specifications for column \"%s\" of table \"%s\"",
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column->colname, cxt->relation->relname),
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parser_errposition(cxt->pstate,
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constraint->location)));
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generateSerialExtraStmts(cxt, column,
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typeOid, constraint->options, true,
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NULL, NULL);
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column->identity = constraint->generated_when;
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saw_identity = true;
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column->is_not_null = TRUE;
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break;
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}
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case CONSTR_CHECK:
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cxt->ckconstraints = lappend(cxt->ckconstraints, constraint);
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break;
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@ -660,6 +749,14 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
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constraint->contype);
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break;
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}
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if (saw_default && saw_identity)
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("both default and identity specified for column \"%s\" of table \"%s\"",
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column->colname, cxt->relation->relname),
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parser_errposition(cxt->pstate,
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constraint->location)));
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}
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/*
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@ -932,6 +1029,27 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
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def->cooked_default = this_default;
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}
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/*
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* Copy identity if requested
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*/
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if (attribute->attidentity &&
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(table_like_clause->options & CREATE_TABLE_LIKE_IDENTITY))
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{
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Oid seq_relid;
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List *seq_options;
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/*
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* find sequence owned by old column; extract sequence parameters;
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* build new create sequence command
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*/
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seq_relid = getOwnedSequence(RelationGetRelid(relation), attribute->attnum);
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seq_options = sequence_options(seq_relid);
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generateSerialExtraStmts(cxt, def,
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InvalidOid, seq_options, true,
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NULL, NULL);
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def->identity = attribute->attidentity;
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}
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/* Likewise, copy storage if requested */
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if (table_like_clause->options & CREATE_TABLE_LIKE_STORAGE)
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def->storage = attribute->attstorage;
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@ -2628,6 +2746,7 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
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case AT_AlterColumnType:
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{
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ColumnDef *def = (ColumnDef *) cmd->def;
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AttrNumber attnum;
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/*
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* For ALTER COLUMN TYPE, transform the USING clause if
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@ -2640,6 +2759,103 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
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EXPR_KIND_ALTER_COL_TRANSFORM);
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}
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/*
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* For identity column, create ALTER SEQUENCE command to
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* change the data type of the sequence.
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*/
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attnum = get_attnum(relid, cmd->name);
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/* if attribute not found, something will error about it later */
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if (attnum != InvalidAttrNumber && get_attidentity(relid, attnum))
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{
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Oid seq_relid = getOwnedSequence(relid, attnum);
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Oid typeOid = typenameTypeId(pstate, def->typeName);
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AlterSeqStmt *altseqstmt = makeNode(AlterSeqStmt);
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altseqstmt->sequence = makeRangeVar(get_namespace_name(get_rel_namespace(seq_relid)),
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get_rel_name(seq_relid),
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-1);
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altseqstmt->options = list_make1(makeDefElem("as", (Node *) makeTypeNameFromOid(typeOid, -1), -1));
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altseqstmt->for_identity = true;
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cxt.blist = lappend(cxt.blist, altseqstmt);
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}
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newcmds = lappend(newcmds, cmd);
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break;
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}
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case AT_AddIdentity:
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{
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Constraint *def = castNode(Constraint, cmd->def);
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ColumnDef *newdef = makeNode(ColumnDef);
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AttrNumber attnum;
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newdef->colname = cmd->name;
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newdef->identity = def->generated_when;
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cmd->def = (Node *) newdef;
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attnum = get_attnum(relid, cmd->name);
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/* if attribute not found, something will error about it later */
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if (attnum != InvalidAttrNumber)
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generateSerialExtraStmts(&cxt, newdef,
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get_atttype(relid, attnum),
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def->options, true,
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NULL, NULL);
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newcmds = lappend(newcmds, cmd);
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break;
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}
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case AT_SetIdentity:
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{
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/*
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* Create an ALTER SEQUENCE statement for the internal
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* sequence of the identity column.
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*/
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ListCell *lc;
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List *newseqopts = NIL;
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List *newdef = NIL;
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List *seqlist;
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AttrNumber attnum;
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/*
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* Split options into those handled by ALTER SEQUENCE and
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* those for ALTER TABLE proper.
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*/
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foreach(lc, castNode(List, cmd->def))
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{
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DefElem *def = castNode(DefElem, lfirst(lc));
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if (strcmp(def->defname, "generated") == 0)
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newdef = lappend(newdef, def);
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else
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newseqopts = lappend(newseqopts, def);
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}
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attnum = get_attnum(relid, cmd->name);
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if (attnum)
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{
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seqlist = getOwnedSequences(relid, attnum);
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if (seqlist)
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{
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AlterSeqStmt *seqstmt;
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Oid seq_relid;
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seqstmt = makeNode(AlterSeqStmt);
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seq_relid = linitial_oid(seqlist);
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seqstmt->sequence = makeRangeVar(get_namespace_name(get_rel_namespace(seq_relid)),
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get_rel_name(seq_relid), -1);
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seqstmt->options = newseqopts;
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seqstmt->for_identity = true;
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seqstmt->missing_ok = false;
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cxt.alist = lappend(cxt.alist, seqstmt);
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}
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}
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/* If column was not found or was not an identity column, we
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* just let the ALTER TABLE command error out later. */
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cmd->def = (Node *) newdef;
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newcmds = lappend(newcmds, cmd);
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break;
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}
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