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;
 }