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postgresql/src/include/commands/dbcommands_xlog.h

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Move WAL-related definitions from dbcommands.h to separate header file. This makes it easier to write frontend programs that needs to understand the WAL record format of CREATE/DROP DATABASE. dbcommands.h cannot easily be #included in a frontend program, because it pulls in other header files that need backend stuff, but the new dbcommands_xlog.h header file has fewer dependencies.
2015-03-09 14:49:10 +01:00
/*-------------------------------------------------------------------------
*
* dbcommands_xlog.h
* Database resource manager XLOG definitions (create/drop database).
*
*
Update copyright for 2022 Backpatch-through: 10
2022-01-08 01:04:57 +01:00
* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
Move WAL-related definitions from dbcommands.h to separate header file. This makes it easier to write frontend programs that needs to understand the WAL record format of CREATE/DROP DATABASE. dbcommands.h cannot easily be #included in a frontend program, because it pulls in other header files that need backend stuff, but the new dbcommands_xlog.h header file has fewer dependencies.
2015-03-09 14:49:10 +01:00
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/commands/dbcommands_xlog.h
*
*-------------------------------------------------------------------------
*/
#ifndef DBCOMMANDS_XLOG_H
#define DBCOMMANDS_XLOG_H
#include "access/xlogreader.h"
#include "lib/stringinfo.h"
/* record types */
Add new block-by-block strategy for CREATE DATABASE. Because this strategy logs changes on a block-by-block basis, it avoids the need to checkpoint before and after the operation. However, because it logs each changed block individually, it might generate a lot of extra write-ahead logging if the template database is large. Therefore, the older strategy remains available via a new STRATEGY parameter to CREATE DATABASE, and a corresponding --strategy option to createdb. Somewhat controversially, this patch assembles the list of relations to be copied to the new database by reading the pg_class relation of the template database. Cross-database access like this isn't normally possible, but it can be made to work here because there can't be any connections to the database being copied, nor can it contain any in-doubt transactions. Even so, we have to use lower-level interfaces than normal, since the table scan and relcache interfaces will not work for a database to which we're not connected. The advantage of this approach is that we do not need to rely on the filesystem to determine what ought to be copied, but instead on PostgreSQL's own knowledge of the database structure. This avoids, for example, copying stray files that happen to be located in the source database directory. Dilip Kumar, with a fairly large number of cosmetic changes by me. Reviewed and tested by Ashutosh Sharma, Andres Freund, John Naylor, Greg Nancarrow, Neha Sharma. Additional feedback from Bruce Momjian, Heikki Linnakangas, Julien Rouhaud, Adam Brusselback, Kyotaro Horiguchi, Tomas Vondra, Andrew Dunstan, Álvaro Herrera, and others. Discussion: http://postgr.es/m/CA+TgmoYtcdxBjLh31DLxUXHxFVMPGzrU5_T=CYCvRyFHywSBUQ@mail.gmail.com
2022-03-29 17:31:43 +02:00
#define XLOG_DBASE_CREATE_FILE_COPY 0x00
#define XLOG_DBASE_CREATE_WAL_LOG 0x10
#define XLOG_DBASE_DROP 0x20
Move WAL-related definitions from dbcommands.h to separate header file. This makes it easier to write frontend programs that needs to understand the WAL record format of CREATE/DROP DATABASE. dbcommands.h cannot easily be #included in a frontend program, because it pulls in other header files that need backend stuff, but the new dbcommands_xlog.h header file has fewer dependencies.
2015-03-09 14:49:10 +01:00
Add new block-by-block strategy for CREATE DATABASE. Because this strategy logs changes on a block-by-block basis, it avoids the need to checkpoint before and after the operation. However, because it logs each changed block individually, it might generate a lot of extra write-ahead logging if the template database is large. Therefore, the older strategy remains available via a new STRATEGY parameter to CREATE DATABASE, and a corresponding --strategy option to createdb. Somewhat controversially, this patch assembles the list of relations to be copied to the new database by reading the pg_class relation of the template database. Cross-database access like this isn't normally possible, but it can be made to work here because there can't be any connections to the database being copied, nor can it contain any in-doubt transactions. Even so, we have to use lower-level interfaces than normal, since the table scan and relcache interfaces will not work for a database to which we're not connected. The advantage of this approach is that we do not need to rely on the filesystem to determine what ought to be copied, but instead on PostgreSQL's own knowledge of the database structure. This avoids, for example, copying stray files that happen to be located in the source database directory. Dilip Kumar, with a fairly large number of cosmetic changes by me. Reviewed and tested by Ashutosh Sharma, Andres Freund, John Naylor, Greg Nancarrow, Neha Sharma. Additional feedback from Bruce Momjian, Heikki Linnakangas, Julien Rouhaud, Adam Brusselback, Kyotaro Horiguchi, Tomas Vondra, Andrew Dunstan, Álvaro Herrera, and others. Discussion: http://postgr.es/m/CA+TgmoYtcdxBjLh31DLxUXHxFVMPGzrU5_T=CYCvRyFHywSBUQ@mail.gmail.com
2022-03-29 17:31:43 +02:00
/*
* Single WAL record for an entire CREATE DATABASE operation. This is used
* by the FILE_COPY strategy.
*/
typedef struct xl_dbase_create_file_copy_rec
Move WAL-related definitions from dbcommands.h to separate header file. This makes it easier to write frontend programs that needs to understand the WAL record format of CREATE/DROP DATABASE. dbcommands.h cannot easily be #included in a frontend program, because it pulls in other header files that need backend stuff, but the new dbcommands_xlog.h header file has fewer dependencies.
2015-03-09 14:49:10 +01:00
{
Oid db_id;
Oid tablespace_id;
Oid src_db_id;
Oid src_tablespace_id;
Add new block-by-block strategy for CREATE DATABASE. Because this strategy logs changes on a block-by-block basis, it avoids the need to checkpoint before and after the operation. However, because it logs each changed block individually, it might generate a lot of extra write-ahead logging if the template database is large. Therefore, the older strategy remains available via a new STRATEGY parameter to CREATE DATABASE, and a corresponding --strategy option to createdb. Somewhat controversially, this patch assembles the list of relations to be copied to the new database by reading the pg_class relation of the template database. Cross-database access like this isn't normally possible, but it can be made to work here because there can't be any connections to the database being copied, nor can it contain any in-doubt transactions. Even so, we have to use lower-level interfaces than normal, since the table scan and relcache interfaces will not work for a database to which we're not connected. The advantage of this approach is that we do not need to rely on the filesystem to determine what ought to be copied, but instead on PostgreSQL's own knowledge of the database structure. This avoids, for example, copying stray files that happen to be located in the source database directory. Dilip Kumar, with a fairly large number of cosmetic changes by me. Reviewed and tested by Ashutosh Sharma, Andres Freund, John Naylor, Greg Nancarrow, Neha Sharma. Additional feedback from Bruce Momjian, Heikki Linnakangas, Julien Rouhaud, Adam Brusselback, Kyotaro Horiguchi, Tomas Vondra, Andrew Dunstan, Álvaro Herrera, and others. Discussion: http://postgr.es/m/CA+TgmoYtcdxBjLh31DLxUXHxFVMPGzrU5_T=CYCvRyFHywSBUQ@mail.gmail.com
2022-03-29 17:31:43 +02:00
} xl_dbase_create_file_copy_rec;
/*
* WAL record for the beginning of a CREATE DATABASE operation, when the
* WAL_LOG strategy is used. Each individual block will be logged separately
* afterward.
*/
typedef struct xl_dbase_create_wal_log_rec
{
Oid db_id;
Oid tablespace_id;
} xl_dbase_create_wal_log_rec;
Move WAL-related definitions from dbcommands.h to separate header file. This makes it easier to write frontend programs that needs to understand the WAL record format of CREATE/DROP DATABASE. dbcommands.h cannot easily be #included in a frontend program, because it pulls in other header files that need backend stuff, but the new dbcommands_xlog.h header file has fewer dependencies.
2015-03-09 14:49:10 +01:00
typedef struct xl_dbase_drop_rec
{
Oid db_id;
Make DROP DATABASE command generate less WAL records. Previously DROP DATABASE generated as many XLOG_DBASE_DROP WAL records as the number of tablespaces that the database to drop uses. This caused the scans of shared_buffers as many times as the number of the tablespaces during recovery because WAL replay of one XLOG_DBASE_DROP record needs that full scan. This could make the recovery time longer especially when shared_buffers is large. This commit changes DROP DATABASE so that it generates only one XLOG_DBASE_DROP record, and registers the information of all the tablespaces into it. Then, WAL replay of XLOG_DBASE_DROP record needs full scan of shared_buffers only once, and which may improve the recovery performance. Author: Fujii Masao Reviewed-by: Kirk Jamison, Simon Riggs Discussion: https://postgr.es/m/CAHGQGwF8YwNH0ZaL+2wjZPkj+ji9UhC+Z4ScnG97WKtVY5L9iw@mail.gmail.com
2019-11-21 13:10:37 +01:00
int ntablespaces; /* number of tablespace IDs */
Oid tablespace_ids[FLEXIBLE_ARRAY_MEMBER];
Move WAL-related definitions from dbcommands.h to separate header file. This makes it easier to write frontend programs that needs to understand the WAL record format of CREATE/DROP DATABASE. dbcommands.h cannot easily be #included in a frontend program, because it pulls in other header files that need backend stuff, but the new dbcommands_xlog.h header file has fewer dependencies.
2015-03-09 14:49:10 +01:00
} xl_dbase_drop_rec;
Make DROP DATABASE command generate less WAL records. Previously DROP DATABASE generated as many XLOG_DBASE_DROP WAL records as the number of tablespaces that the database to drop uses. This caused the scans of shared_buffers as many times as the number of the tablespaces during recovery because WAL replay of one XLOG_DBASE_DROP record needs that full scan. This could make the recovery time longer especially when shared_buffers is large. This commit changes DROP DATABASE so that it generates only one XLOG_DBASE_DROP record, and registers the information of all the tablespaces into it. Then, WAL replay of XLOG_DBASE_DROP record needs full scan of shared_buffers only once, and which may improve the recovery performance. Author: Fujii Masao Reviewed-by: Kirk Jamison, Simon Riggs Discussion: https://postgr.es/m/CAHGQGwF8YwNH0ZaL+2wjZPkj+ji9UhC+Z4ScnG97WKtVY5L9iw@mail.gmail.com
2019-11-21 13:10:37 +01:00
#define MinSizeOfDbaseDropRec offsetof(xl_dbase_drop_rec, tablespace_ids)
Move WAL-related definitions from dbcommands.h to separate header file. This makes it easier to write frontend programs that needs to understand the WAL record format of CREATE/DROP DATABASE. dbcommands.h cannot easily be #included in a frontend program, because it pulls in other header files that need backend stuff, but the new dbcommands_xlog.h header file has fewer dependencies.
2015-03-09 14:49:10 +01:00
extern void dbase_redo(XLogReaderState *rptr);
extern void dbase_desc(StringInfo buf, XLogReaderState *rptr);
extern const char *dbase_identify(uint8 info);
#endif /* DBCOMMANDS_XLOG_H */