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pg_basebackup: Add support for relocating tablespaces

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Tablespaces can be relocated in plain backup mode by specifying one or
more -T olddir=newdir options.

Author: Steeve Lennmark <steevel@handeldsbanken.se>
Reviewed-by: Peter Eisentraut <peter_e@gmx.net>
This commit is contained in:
Peter Eisentraut
2014-02-22 13:38:06 -05:00
parent 77585bce03
commit fb05f3ce83
2 changed files with 204 additions and 8 deletions
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166
src/bin/pg_basebackup/pg_basebackup.c
View File

@@ -35,8 +35,24 @@
#include "streamutil.h"
#define atooid(x) ((Oid) strtoul((x), NULL, 10))
typedef struct TablespaceListCell
{
struct TablespaceListCell *next;
char old_dir[MAXPGPATH];
char new_dir[MAXPGPATH];
} TablespaceListCell;
typedef struct TablespaceList
{
TablespaceListCell *head;
TablespaceListCell *tail;
} TablespaceList;
/* Global options */
static char *basedir = NULL;
static TablespaceList tablespace_dirs = {NULL, NULL};
static char *xlog_dir = "";
static char format = 'p'; /* p(lain)/t(ar) */
static char *label = "pg_basebackup base backup";
@@ -90,6 +106,10 @@ static void BaseBackup(void);
static bool reached_end_position(XLogRecPtr segendpos, uint32 timeline,
bool segment_finished);
static const char *get_tablespace_mapping(const char *dir);
static void update_tablespace_symlink(Oid oid, const char *old_dir);
static void tablespace_list_append(const char *arg);
static void disconnect_and_exit(int code)
{
@@ -110,6 +130,77 @@ static void disconnect_and_exit(int code)
}
/*
* Split argument into old_dir and new_dir and append to tablespace mapping
* list.
*/
static void
tablespace_list_append(const char *arg)
{
TablespaceListCell *cell = (TablespaceListCell *) pg_malloc0(sizeof(TablespaceListCell));
char *dst;
char *dst_ptr;
const char *arg_ptr;
dst_ptr = dst = cell->old_dir;
for (arg_ptr = arg; *arg_ptr; arg_ptr++)
{
if (dst_ptr - dst >= MAXPGPATH)
{
fprintf(stderr, _("%s: directory name too long\n"), progname);
exit(1);
}
if (*arg_ptr == '\\' && *(arg_ptr + 1) == '=')
; /* skip backslash escaping = */
else if (*arg_ptr == '=' && (arg_ptr == arg || *(arg_ptr - 1) != '\\'))
{
if (*cell->new_dir)
{
fprintf(stderr, _("%s: multiple \"=\" signs in tablespace mapping\n"), progname);
exit(1);
}
else
dst = dst_ptr = cell->new_dir;
}
else
*dst_ptr++ = *arg_ptr;
}
if (!*cell->old_dir || !*cell->new_dir)
{
fprintf(stderr,
_("%s: invalid tablespace mapping format \"%s\", must be \"OLDDIR=NEWDIR\"\n"),
progname, arg);
exit(1);
}
/* This check isn't absolutely necessary. But all tablespaces are created
* with absolute directories, so specifying a non-absolute path here would
* just never match, possibly confusing users. It's also good to be
* consistent with the new_dir check. */
if (!is_absolute_path(cell->old_dir))
{
fprintf(stderr, _("%s: old directory not absolute in tablespace mapping: %s\n"),
progname, cell->old_dir);
exit(1);
}
if (!is_absolute_path(cell->new_dir))
{
fprintf(stderr, _("%s: new directory not absolute in tablespace mapping: %s\n"),
progname, cell->new_dir);
exit(1);
}
if (tablespace_dirs.tail)
tablespace_dirs.tail->next = cell;
else
tablespace_dirs.head = cell;
tablespace_dirs.tail = cell;
}
#ifdef HAVE_LIBZ
static const char *
get_gz_error(gzFile gzf)
@@ -137,6 +228,8 @@ usage(void)
printf(_(" -F, --format=p|t output format (plain (default), tar)\n"));
printf(_(" -R, --write-recovery-conf\n"
" write recovery.conf after backup\n"));
printf(_(" -T, --tablespace-mapping=OLDDIR=NEWDIR\n"
" relocate tablespace in OLDDIR to NEWDIR\n"));
printf(_(" -x, --xlog include required WAL files in backup (fetch mode)\n"));
printf(_(" -X, --xlog-method=fetch|stream\n"
" include required WAL files with specified method\n"));
@@ -899,6 +992,52 @@ ReceiveTarFile(PGconn *conn, PGresult *res, int rownum)
PQfreemem(copybuf);
}
/*
* Retrieve tablespace path, either relocated or original depending on whether
* -T was passed or not.
*/
static const char *
get_tablespace_mapping(const char *dir)
{
TablespaceListCell *cell;
for (cell = tablespace_dirs.head; cell; cell = cell->next)
if (strcmp(dir, cell->old_dir) == 0)
return cell->new_dir;
return dir;
}
/*
* Update symlinks to reflect relocated tablespace.
*/
static void
update_tablespace_symlink(Oid oid, const char *old_dir)
{
const char *new_dir = get_tablespace_mapping(old_dir);
if (strcmp(old_dir, new_dir) != 0)
{
char *linkloc = psprintf("%s/pg_tblspc/%d", basedir, oid);
if (unlink(linkloc) != 0 && errno != ENOENT)
{
fprintf(stderr, _("%s: could not remove symbolic link \"%s\": %s"),
progname, linkloc, strerror(errno));
disconnect_and_exit(1);
}
if (symlink(new_dir, linkloc) != 0)
{
fprintf(stderr, _("%s: could not create symbolic link \"%s\": %s"),
progname, linkloc, strerror(errno));
disconnect_and_exit(1);
}
}
}
/*
* Receive a tar format stream from the connection to the server, and unpack
* the contents of it into a directory. Only files, directories and
@@ -906,8 +1045,7 @@ ReceiveTarFile(PGconn *conn, PGresult *res, int rownum)
*
* If the data is for the main data directory, it will be restored in the
* specified directory. If it's for another tablespace, it will be restored
* in the original directory, since relocation of tablespaces is not
* supported.
* in the original or mapped directory.
*/
static void
ReceiveAndUnpackTarFile(PGconn *conn, PGresult *res, int rownum)
@@ -923,7 +1061,7 @@ ReceiveAndUnpackTarFile(PGconn *conn, PGresult *res, int rownum)
if (basetablespace)
strlcpy(current_path, basedir, sizeof(current_path));
else
strlcpy(current_path, PQgetvalue(res, rownum, 1), sizeof(current_path));
strlcpy(current_path, get_tablespace_mapping(PQgetvalue(res, rownum, 1)), sizeof(current_path));
/*
* Get the COPY data
@@ -1503,7 +1641,10 @@ BaseBackup(void)
* we do anything anyway.
*/
if (format == 'p' && !PQgetisnull(res, i, 1))
verify_dir_is_empty_or_create(PQgetvalue(res, i, 1));
{
char *path = (char *) get_tablespace_mapping(PQgetvalue(res, i, 1));
verify_dir_is_empty_or_create(path);
}
}
/*
@@ -1545,6 +1686,17 @@ BaseBackup(void)
progress_report(PQntuples(res), NULL, true);
fprintf(stderr, "\n"); /* Need to move to next line */
}
if (format == 'p' && tablespace_dirs.head != NULL)
{
for (i = 0; i < PQntuples(res); i++)
{
Oid tblspc_oid = atooid(PQgetvalue(res, i, 0));
if (tblspc_oid)
update_tablespace_symlink(tblspc_oid, PQgetvalue(res, i, 1));
}
}
PQclear(res);
/*
@@ -1696,6 +1848,7 @@ main(int argc, char **argv)
{"format", required_argument, NULL, 'F'},
{"checkpoint", required_argument, NULL, 'c'},
{"write-recovery-conf", no_argument, NULL, 'R'},
{"tablespace-mapping", required_argument, NULL, 'T'},
{"xlog", no_argument, NULL, 'x'},
{"xlog-method", required_argument, NULL, 'X'},
{"gzip", no_argument, NULL, 'z'},
@@ -1735,7 +1888,7 @@ main(int argc, char **argv)
}
}
while ((c = getopt_long(argc, argv, "D:F:RxX:l:zZ:d:c:h:p:U:s:wWvP",
while ((c = getopt_long(argc, argv, "D:F:RT:xX:l:zZ:d:c:h:p:U:s:wWvP",
long_options, &option_index)) != -1)
{
switch (c)
@@ -1759,6 +1912,9 @@ main(int argc, char **argv)
case 'R':
writerecoveryconf = true;
break;
case 'T':
tablespace_list_append(optarg);
break;
case 'x':
if (includewal)
{