postgresql/src/include/parser/parse_utilcmd.h

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/*-------------------------------------------------------------------------
*
* parse_utilcmd.h
* parse analysis for utility commands
*
*
* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
2010-09-20 22:08:53 +02:00
* src/include/parser/parse_utilcmd.h
*
*-------------------------------------------------------------------------
*/
#ifndef PARSE_UTILCMD_H
#define PARSE_UTILCMD_H
#include "parser/parse_node.h"
struct AttrMap; /* avoid including attmap.h here */
extern List *transformCreateStmt(CreateStmt *stmt, const char *queryString);
Restructure ALTER TABLE execution to fix assorted bugs. We've had numerous bug reports about how (1) IF NOT EXISTS clauses in ALTER TABLE don't behave as-expected, and (2) combining certain actions into one ALTER TABLE doesn't work, though executing the same actions as separate statements does. This patch cleans up all of the cases so far reported from the field, though there are still some oddities associated with identity columns. The core problem behind all of these bugs is that we do parse analysis of ALTER TABLE subcommands too soon, before starting execution of the statement. The root of the bugs in group (1) is that parse analysis schedules derived commands (such as a CREATE SEQUENCE for a serial column) before it's known whether the IF NOT EXISTS clause should cause a subcommand to be skipped. The root of the bugs in group (2) is that earlier subcommands may change the catalog state that later subcommands need to be parsed against. Hence, postpone parse analysis of ALTER TABLE's subcommands, and do that one subcommand at a time, during "phase 2" of ALTER TABLE which is the phase that does catalog rewrites. Thus the catalog effects of earlier subcommands are already visible when we analyze later ones. (The sole exception is that we do parse analysis for ALTER COLUMN TYPE subcommands during phase 1, so that their USING expressions can be parsed against the table's original state, which is what we need. Arguably, these bugs stem from falsely concluding that because ALTER COLUMN TYPE must do early parse analysis, every other command subtype can too.) This means that ALTER TABLE itself must deal with execution of any non-ALTER-TABLE derived statements that are generated by parse analysis. Add a suitable entry point to utility.c to accept those recursive calls, and create a struct to pass through the information needed by the recursive call, rather than making the argument lists of AlterTable() and friends even longer. Getting this to work correctly required a little bit of fiddling with the subcommand pass structure, in particular breaking up AT_PASS_ADD_CONSTR into multiple passes. But otherwise it's mostly a pretty straightforward application of the above ideas. Fixing the residual issues for identity columns requires refactoring of where the dependency link from an identity column to its sequence gets set up. So that seems like suitable material for a separate patch, especially since this one is pretty big already. Discussion: https://postgr.es/m/10365.1558909428@sss.pgh.pa.us
2020-01-16 00:49:24 +01:00
extern AlterTableStmt *transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
const char *queryString,
List **beforeStmts,
List **afterStmts);
extern IndexStmt *transformIndexStmt(Oid relid, IndexStmt *stmt,
const char *queryString);
Extended statistics on expressions Allow defining extended statistics on expressions, not just just on simple column references. With this commit, expressions are supported by all existing extended statistics kinds, improving the same types of estimates. A simple example may look like this: CREATE TABLE t (a int); CREATE STATISTICS s ON mod(a,10), mod(a,20) FROM t; ANALYZE t; The collected statistics are useful e.g. to estimate queries with those expressions in WHERE or GROUP BY clauses: SELECT * FROM t WHERE mod(a,10) = 0 AND mod(a,20) = 0; SELECT 1 FROM t GROUP BY mod(a,10), mod(a,20); This introduces new internal statistics kind 'e' (expressions) which is built automatically when the statistics object definition includes any expressions. This represents single-expression statistics, as if there was an expression index (but without the index maintenance overhead). The statistics is stored in pg_statistics_ext_data as an array of composite types, which is possible thanks to 79f6a942bd. CREATE STATISTICS allows building statistics on a single expression, in which case in which case it's not possible to specify statistics kinds. A new system view pg_stats_ext_exprs can be used to display expression statistics, similarly to pg_stats and pg_stats_ext views. ALTER TABLE ... ALTER COLUMN ... TYPE now treats indexes the same way it treats indexes, i.e. it drops and recreates the statistics. This means all statistics are reset, and we no longer try to preserve at least the functional dependencies. This should not be a major issue in practice, as the functional dependencies actually rely on per-column statistics, which were always reset anyway. Author: Tomas Vondra Reviewed-by: Justin Pryzby, Dean Rasheed, Zhihong Yu Discussion: https://postgr.es/m/ad7891d2-e90c-b446-9fe2-7419143847d7%40enterprisedb.com
2021-03-26 23:22:01 +01:00
extern CreateStatsStmt *transformStatsStmt(Oid relid, CreateStatsStmt *stmt,
const char *queryString);
extern void transformRuleStmt(RuleStmt *stmt, const char *queryString,
List **actions, Node **whereClause);
extern List *transformCreateSchemaStmt(CreateSchemaStmt *stmt);
Code review focused on new node types added by partitioning support. Fix failure to check that we got a plain Const from const-simplification of a coercion request. This is the cause of bug #14666 from Tian Bing: there is an int4 to money cast, but it's only stable not immutable (because of dependence on lc_monetary), resulting in a FuncExpr that the code was miserably unequipped to deal with, or indeed even to notice that it was failing to deal with. Add test cases around this coercion behavior. In view of the above, sprinkle the code liberally with castNode() macros, in hope of catching the next such bug a bit sooner. Also, change some functions that were randomly declared to take Node* to take more specific pointer types. And change some struct fields that were declared Node* but could be given more specific types, allowing removal of assorted explicit casts. Place PARTITION_MAX_KEYS check a bit closer to the code it's protecting. Likewise check only-one-key-for-list-partitioning restriction in a less random place. Avoid not-per-project-style usages like !strcmp(...). Fix assorted failures to avoid scribbling on the input of parse transformation. I'm not sure how necessary this is, but it's entirely silly for these functions to be expending cycles to avoid that and not getting it right. Add guards against partitioning on system columns. Put backend/nodes/ support code into an order that matches handling of these node types elsewhere. Annotate the fact that somebody added location fields to PartitionBoundSpec and PartitionRangeDatum but forgot to handle them in outfuncs.c/readfuncs.c. This is fairly harmless for production purposes (since readfuncs.c would just substitute -1 anyway) but it's still bogus. It's not worth forcing a post-beta1 initdb just to fix this, but if we have another reason to force initdb before 10.0, we should go back and clean this up. Contrariwise, somebody added location fields to PartitionElem and PartitionSpec but forgot to teach exprLocation() about them. Consolidate duplicative code in transformPartitionBound(). Improve a couple of error messages. Improve assorted commentary. Re-pgindent the files touched by this patch; this affects a few comment blocks that must have been added quite recently. Report: https://postgr.es/m/20170524024550.29935.14396@wrigleys.postgresql.org
2017-05-29 05:20:28 +02:00
extern PartitionBoundSpec *transformPartitionBound(ParseState *pstate, Relation parent,
PartitionBoundSpec *spec);
extern List *expandTableLikeClause(RangeVar *heapRel,
TableLikeClause *table_like_clause);
Avoid order-of-execution problems with ALTER TABLE ADD PRIMARY KEY. Up to now, DefineIndex() was responsible for adding attnotnull constraints to the columns of a primary key, in any case where it hadn't been convenient for transformIndexConstraint() to mark those columns as is_not_null. It (or rather its minion index_check_primary_key) did this by executing an ALTER TABLE SET NOT NULL command for the target table. The trouble with this solution is that if we're creating the index due to ALTER TABLE ADD PRIMARY KEY, and the outer ALTER TABLE has additional sub-commands, the inner ALTER TABLE's operations executed at the wrong time with respect to the outer ALTER TABLE's operations. In particular, the inner ALTER would perform a validation scan at a point where the table's storage might be inconsistent with its catalog entries. (This is on the hairy edge of being a security problem, but AFAICS it isn't one because the inner scan would only be interested in the tuples' null bitmaps.) This can result in unexpected failures, such as the one seen in bug #15580 from Allison Kaptur. To fix, let's remove the attempt to do SET NOT NULL from DefineIndex(), reducing index_check_primary_key's role to verifying that the columns are already not null. (It shouldn't ever see such a case, but it seems wise to keep the check for safety.) Instead, make transformIndexConstraint() generate ALTER TABLE SET NOT NULL subcommands to be executed ahead of the ADD PRIMARY KEY operation in every case where it can't force the column to be created already-not-null. This requires only minor surgery in parse_utilcmd.c, and it makes for a much more satisfying spec for transformIndexConstraint(): it's no longer having to take it on faith that someone else will handle addition of NOT NULL constraints. To make that work, we have to move the execution of AT_SetNotNull into an ALTER pass that executes ahead of AT_PASS_ADD_INDEX. I moved it to AT_PASS_COL_ATTRS, and put that after AT_PASS_ADD_COL to avoid failure when the column is being added in the same command. This incidentally fixes a bug in the only previous usage of AT_PASS_COL_ATTRS, for AT_SetIdentity: it didn't work either for a newly-added column. Playing around with this exposed a separate bug in ALTER TABLE ONLY ... ADD PRIMARY KEY for partitioned tables. The intent of the ONLY modifier in that context is to prevent doing anything that would require holding lock for a long time --- but the implied SET NOT NULL would recurse to the child partitions, and do an expensive validation scan for any child where the column(s) were not already NOT NULL. To fix that, invent a new ALTER subcommand AT_CheckNotNull that just insists that a child column be already NOT NULL, and apply that, not AT_SetNotNull, when recursing to children in this scenario. This results in a slightly laxer definition of ALTER TABLE ONLY ... SET NOT NULL for partitioned tables, too: that command will now work as long as all children are already NOT NULL, whereas before it just threw up its hands if there were any partitions. In passing, clean up the API of generateClonedIndexStmt(): remove a useless argument, ensure that the output argument is not left undefined, update the header comment. A small side effect of this change is that no-such-column errors in ALTER TABLE ADD PRIMARY KEY now produce a different message that includes the table name, because they are now detected by the SET NOT NULL step which has historically worded its error that way. That seems fine to me, so I didn't make any effort to avoid the wording change. The basic bug #15580 is of very long standing, and these other bugs aren't new in v12 either. However, this is a pretty significant change in the way ALTER TABLE ADD PRIMARY KEY works. On balance it seems best not to back-patch, at least not till we get some more confidence that this patch has no new bugs. Patch by me, but thanks to Jie Zhang for a preliminary version. Discussion: https://postgr.es/m/15580-d1a6de5a3d65da51@postgresql.org Discussion: https://postgr.es/m/1396E95157071C4EBBA51892C5368521017F2E6E63@G08CNEXMBPEKD02.g08.fujitsu.local
2019-04-23 18:25:27 +02:00
extern IndexStmt *generateClonedIndexStmt(RangeVar *heapRel,
Relation source_idx,
const struct AttrMap *attmap,
Oid *constraintOid);
#endif /* PARSE_UTILCMD_H */