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MasaoFujiiMasaoFujii
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Add pg_file_sync() to adminpack extension.
This function allows us to fsync the specified file or directory. It's useful, for example, when we want to sync the file that pg_file_write() writes out or that COPY TO exports the data into, for durability. Author: Fujii Masao Reviewed-By: Julien Rouhaud, Arthur Zakirov, Michael Paquier, Atsushi Torikoshi Discussion: https://www.postgresql.org/message-id/CAHGQGwGY8uzZ_k8dHRoW1zDcy1Z7=5GQ+So4ZkVy2u=nLsk=hA@mail.gmail.com
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-4
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9 files changed

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‎contrib/adminpack/Makefile

+2-1
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,8 @@ OBJS = \
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PG_CPPFLAGS = -I$(libpq_srcdir)
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EXTENSION = adminpack
10-
DATA = adminpack--1.0.sql adminpack--1.0--1.1.sql adminpack--1.1--2.0.sql
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DATA = adminpack--1.0.sql adminpack--1.0--1.1.sql adminpack--1.1--2.0.sql\
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adminpack--2.0--2.1.sql
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PGFILEDESC = "adminpack - support functions for pgAdmin"
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REGRESS = adminpack

‎contrib/adminpack/adminpack--2.0--2.1.sql

+17
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,17 @@
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/* contrib/adminpack/adminpack--2.0--2.1.sql */
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-- complain if script is sourced in psql, rather than via ALTER EXTENSION
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\echo Use "ALTER EXTENSION adminpack UPDATE TO '2.1'" to load this file. \quit
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/* ***********************************************
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* Administrative functions for PostgreSQL
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* *********************************************** */
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/* generic file access functions */
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CREATE OR REPLACE FUNCTION pg_catalog.pg_file_sync(text)
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RETURNS void
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AS 'MODULE_PATHNAME', 'pg_file_sync'
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LANGUAGE C VOLATILE STRICT;
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REVOKE EXECUTE ON FUNCTION pg_catalog.pg_file_sync(text) FROM PUBLIC;

‎contrib/adminpack/adminpack.c

+25
Original file line numberDiff line numberDiff line change
@@ -43,6 +43,7 @@ PG_MODULE_MAGIC;
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PG_FUNCTION_INFO_V1(pg_file_write);
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PG_FUNCTION_INFO_V1(pg_file_write_v1_1);
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PG_FUNCTION_INFO_V1(pg_file_sync);
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PG_FUNCTION_INFO_V1(pg_file_rename);
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PG_FUNCTION_INFO_V1(pg_file_rename_v1_1);
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PG_FUNCTION_INFO_V1(pg_file_unlink);
@@ -215,6 +216,30 @@ pg_file_write_internal(text *file, text *data, bool replace)
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return (count);
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}
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/* ------------------------------------
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* pg_file_sync
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*
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* We REVOKE EXECUTE on the function from PUBLIC.
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* Users can then grant access to it based on their policies.
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*/
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Datum
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pg_file_sync(PG_FUNCTION_ARGS)
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{
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char *filename;
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struct stat fst;
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filename = convert_and_check_filename(PG_GETARG_TEXT_PP(0), false);
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if (stat(filename, &fst) < 0)
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ereport(ERROR,
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(errcode_for_file_access(),
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errmsg("could not stat file \"%s\": %m", filename)));
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fsync_fname_ext(filename, S_ISDIR(fst.st_mode), false, ERROR);
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PG_RETURN_VOID();
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}
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/* ------------------------------------
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* pg_file_rename - old version
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*

‎contrib/adminpack/adminpack.control

+1-1
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,6 @@
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# adminpack extension
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comment = 'administrative functions for PostgreSQL'
3-
default_version = '2.0'
3+
default_version = '2.1'
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module_pathname = '$libdir/adminpack'
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relocatable = false
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schema = pg_catalog

‎contrib/adminpack/expected/adminpack.out

+17
Original file line numberDiff line numberDiff line change
@@ -56,6 +56,21 @@ RESET ROLE;
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REVOKE EXECUTE ON FUNCTION pg_file_write(text,text,bool) FROM regress_user1;
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REVOKE pg_read_all_settings FROM regress_user1;
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DROP ROLE regress_user1;
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-- sync
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SELECT pg_file_sync('test_file1'); -- sync file
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pg_file_sync
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--------------
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(1 row)
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SELECT pg_file_sync('pg_stat'); -- sync directory
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pg_file_sync
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--------------
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(1 row)
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SELECT pg_file_sync('test_file2'); -- not there
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ERROR: could not stat file "test_file2": No such file or directory
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-- rename file
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SELECT pg_file_rename('test_file1', 'test_file2');
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pg_file_rename
@@ -142,6 +157,8 @@ CREATE USER regress_user1;
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SET ROLE regress_user1;
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SELECT pg_file_write('test_file0', 'test0', false);
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ERROR: permission denied for function pg_file_write
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SELECT pg_file_sync('test_file0');
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ERROR: permission denied for function pg_file_sync
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SELECT pg_file_rename('test_file0', 'test_file0');
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ERROR: permission denied for function pg_file_rename
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CONTEXT: SQL function "pg_file_rename" statement 1

‎contrib/adminpack/sql/adminpack.sql

+6
Original file line numberDiff line numberDiff line change
@@ -29,6 +29,11 @@ REVOKE EXECUTE ON FUNCTION pg_file_write(text,text,bool) FROM regress_user1;
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REVOKE pg_read_all_settings FROM regress_user1;
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DROP ROLE regress_user1;
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-- sync
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SELECT pg_file_sync('test_file1'); -- sync file
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SELECT pg_file_sync('pg_stat'); -- sync directory
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SELECT pg_file_sync('test_file2'); -- not there
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-- rename file
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SELECT pg_file_rename('test_file1', 'test_file2');
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SELECT pg_read_file('test_file1'); -- not there
@@ -58,6 +63,7 @@ CREATE USER regress_user1;
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SET ROLE regress_user1;
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SELECT pg_file_write('test_file0', 'test0', false);
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SELECT pg_file_sync('test_file0');
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SELECT pg_file_rename('test_file0', 'test_file0');
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SELECT pg_file_unlink('test_file0');
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SELECT pg_logdir_ls();

‎doc/src/sgml/adminpack.sgml

+19
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@@ -43,6 +43,13 @@
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Write, or append to, a text file
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</entry>
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</row>
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<row>
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<entry><function>pg_catalog.pg_file_sync(filename text)</function></entry>
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<entry><type>void</type></entry>
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<entry>
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Flush a file or directory to disk
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</entry>
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</row>
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<row>
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<entry><function>pg_catalog.pg_file_rename(oldname text, newname text <optional>, archivename text</optional>)</function></entry>
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<entry><type>boolean</type></entry>
@@ -79,6 +86,18 @@
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Returns the number of bytes written.
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</para>
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<indexterm>
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<primary>pg_file_sync</primary>
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</indexterm>
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<para>
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<function>pg_file_sync</function> fsyncs the specified file or directory
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named by <parameter>filename</parameter>. An error is thrown
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on failure (e.g., the specified file is not present). Note that
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<xref linkend="guc-data-sync-retry"/> has no effect on this function,
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and therefore a PANIC-level error will not be raised even on failure to
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flush database files.
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</para>
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82101
<indexterm>
83102
<primary>pg_file_rename</primary>
84103
</indexterm>

‎src/backend/storage/file/fd.c

+1-2
Original file line numberDiff line numberDiff line change
@@ -319,7 +319,6 @@ static void pre_sync_fname(const char *fname, bool isdir, int elevel);
319319
static void datadir_fsync_fname(const char *fname, bool isdir, int elevel);
320320
static void unlink_if_exists_fname(const char *fname, bool isdir, int elevel);
321321

322-
static int fsync_fname_ext(const char *fname, bool isdir, bool ignore_perm, int elevel);
323322
static int fsync_parent_path(const char *fname, int elevel);
324323

325324

@@ -3376,7 +3375,7 @@ unlink_if_exists_fname(const char *fname, bool isdir, int elevel)
33763375
*
33773376
* Returns 0 if the operation succeeded, -1 otherwise.
33783377
*/
3379-
static int
3378+
int
33803379
fsync_fname_ext(const char *fname, bool isdir, bool ignore_perm, int elevel)
33813380
{
33823381
int fd;

‎src/include/storage/fd.h

+1
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@@ -145,6 +145,7 @@ extern int pg_fsync_writethrough(int fd);
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extern int pg_fdatasync(int fd);
146146
extern void pg_flush_data(int fd, off_t offset, off_t amount);
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extern void fsync_fname(const char *fname, bool isdir);
148+
extern int fsync_fname_ext(const char *fname, bool isdir, bool ignore_perm, int elevel);
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extern int durable_rename(const char *oldfile, const char *newfile, int loglevel);
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extern int durable_unlink(const char *fname, int loglevel);
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extern int durable_link_or_rename(const char *oldfile, const char *newfile, int loglevel);

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