Fix pg_rewind with in-place tablespaces when source is remote

libpq_source.c would consider any result returned by
pg_tablespace_location() as a symlink, resulting in run-time errors like
that:
pg_rewind: error: file "pg_tblspc/NN" is of different type in source and target

In-place tablespaces are directories located in pg_tblspc/, returned as
relative paths instead of absolute paths, so rely on that to make the
difference with a normal tablespace and an in-place one.  If the path is
relative, the tablespace is handled as a directory.  If the path is
absolute, consider it as a symlink.

In-place tablespaces are only intended for development purposes, so like
363e8f9 no backpatch is done.  A test is added in pg_rewind with an
in-place tablespace and some data in it.

Author: Rui Zhao, Michael Paquier
Discussion: https://postgr.es/m/2b79d2a8-b2d5-4bd7-a15b-31e485100980.xiyuan.zr@alibaba-inc.com

diff --git a/src/bin/pg_rewind/libpq_source.c b/src/bin/pg_rewind/libpq_source.c
index 0d8e9ee2d1a7390d8328cb313a13f1444f812ab4..417c74cfefcb22e27f212275a64eadf50c4791b7 100644 (file)
--- a/src/bin/pg_rewind/libpq_source.c
+++ b/src/bin/pg_rewind/libpq_source.c
@@ -298,7 +298,16 @@ libpq_traverse_files(rewind_source *source, process_file_callback_t callback)
                link_target = PQgetvalue(res, i, 3);
 
                if (link_target[0])
-                       type = FILE_TYPE_SYMLINK;
+               {
+                       /*
+                        * In-place tablespaces are directories located in pg_tblspc/ with
+                        * relative paths.
+                        */
+                       if (is_absolute_path(link_target))
+                               type = FILE_TYPE_SYMLINK;
+                       else
+                               type = FILE_TYPE_DIRECTORY;
+               }
                else if (isdir)
                        type = FILE_TYPE_DIRECTORY;
                else

diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 031594e14e68698ed63ec29a9cfcf3fca06e5c2c..c7b48255a71101fbde610e6504da243a8551be05 100644 (file)
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -18,6 +18,12 @@ sub run_test
        RewindTest::setup_cluster($test_mode);
        RewindTest::start_primary();
 
+       # Create an in-place tablespace with some data on it.
+       primary_psql("CREATE TABLESPACE space_test LOCATION ''");
+       primary_psql("CREATE TABLE space_tbl (d text) TABLESPACE space_test");
+       primary_psql(
+               "INSERT INTO space_tbl VALUES ('in primary, before promotion')");
+
        # Create a test table and insert a row in primary.
        primary_psql("CREATE TABLE tbl1 (d text)");
        primary_psql("INSERT INTO tbl1 VALUES ('in primary')");
@@ -78,6 +84,13 @@ sub run_test
                "insert into drop_tbl values ('in primary, after promotion')");
        primary_psql("DROP TABLE drop_tbl");
 
+       # Insert some data in the in-place tablespace for the old primary and
+       # the standby.
+       primary_psql(
+               "INSERT INTO space_tbl VALUES ('in primary, after promotion')");
+       standby_psql(
+               "INSERT INTO space_tbl VALUES ('in standby, after promotion')");
+
        # Before running pg_rewind, do a couple of extra tests with several
        # option combinations.  As the code paths taken by those tests
        # do not change for the "local" and "remote" modes, just run them
@@ -145,6 +158,13 @@ sub run_test
 
        RewindTest::run_pg_rewind($test_mode);
 
+       check_query(
+               'SELECT * FROM space_tbl ORDER BY d',
+               qq(in primary, before promotion
+in standby, after promotion
+),
+               'table content');
+
        check_query(
                'SELECT * FROM tbl1',
                qq(in primary

diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 4957791e94dfc855e92f35695c2a97ce8eda4d62..8fbbd521cb5bebdb52faf88c95866390ce9fa758 100644 (file)
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -131,6 +131,7 @@ sub setup_cluster
        $node_primary->append_conf(
                'postgresql.conf', qq(
 wal_keep_size = 320MB
+allow_in_place_tablespaces = on
 ));
        return;
 }