add documentation for new refresh command

[nominatim.git] / nominatim / db / utils.py

diff --git a/nominatim/db/utils.py b/nominatim/db/utils.py
index abd72519fd0d9cbea758795f1bc49643cd8a8842..87b0545fc5ecba66a956219cfbf247e633c16eaf 100644 (file)
--- a/nominatim/db/utils.py
+++ b/nominatim/db/utils.py
@@ -1,12 +1,113 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# This file is part of Nominatim. (https://nominatim.org)
+#
+# Copyright (C) 2022 by the Nominatim developer community.
+# For a full list of authors see the git log.
 """
 Helper functions for handling DB accesses.
 """
+import subprocess
+import logging
+import gzip
+import io
 
-def execute_file(conn, fname):
-    """ Read an SQL file and run its contents against the given connection.
+from nominatim.db.connection import get_pg_env
+from nominatim.errors import UsageError
+
+LOG = logging.getLogger()
+
+def _pipe_to_proc(proc, fdesc):
+    chunk = fdesc.read(2048)
+    while chunk and proc.poll() is None:
+        try:
+            proc.stdin.write(chunk)
+        except BrokenPipeError as exc:
+            raise UsageError("Failed to execute SQL file.") from exc
+        chunk = fdesc.read(2048)
+
+    return len(chunk)
+
+def execute_file(dsn, fname, ignore_errors=False, pre_code=None, post_code=None):
+    """ Read an SQL file and run its contents against the given database
+        using psql. Use `pre_code` and `post_code` to run extra commands
+        before or after executing the file. The commands are run within the
+        same session, so they may be used to wrap the file execution in a
+        transaction.
     """
-    with fname.open('r') as fdesc:
-        sql = fdesc.read()
-    with conn.cursor() as cur:
-        cur.execute(sql)
-    conn.commit()
+    cmd = ['psql']
+    if not ignore_errors:
+        cmd.extend(('-v', 'ON_ERROR_STOP=1'))
+    if not LOG.isEnabledFor(logging.INFO):
+        cmd.append('--quiet')
+    proc = subprocess.Popen(cmd, env=get_pg_env(dsn), stdin=subprocess.PIPE)
+
+    try:
+        if not LOG.isEnabledFor(logging.INFO):
+            proc.stdin.write('set client_min_messages to WARNING;'.encode('utf-8'))
+
+        if pre_code:
+            proc.stdin.write((pre_code + ';').encode('utf-8'))
+
+        if fname.suffix == '.gz':
+            with gzip.open(str(fname), 'rb') as fdesc:
+                remain = _pipe_to_proc(proc, fdesc)
+        else:
+            with fname.open('rb') as fdesc:
+                remain = _pipe_to_proc(proc, fdesc)
+
+        if remain == 0 and post_code:
+            proc.stdin.write((';' + post_code).encode('utf-8'))
+    finally:
+        proc.stdin.close()
+        ret = proc.wait()
+
+    if ret != 0 or remain > 0:
+        raise UsageError("Failed to execute SQL file.")
+
+
+# List of characters that need to be quoted for the copy command.
+_SQL_TRANSLATION = {ord(u'\\'): u'\\\\',
+                    ord(u'\t'): u'\\t',
+                    ord(u'\n'): u'\\n'}
+
+
+class CopyBuffer:
+    """ Data collector for the copy_from command.
+    """
+
+    def __init__(self):
+        self.buffer = io.StringIO()
+
+
+    def __enter__(self):
+        return self
+
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        if self.buffer is not None:
+            self.buffer.close()
+
+
+    def add(self, *data):
+        """ Add another row of data to the copy buffer.
+        """
+        first = True
+        for column in data:
+            if first:
+                first = False
+            else:
+                self.buffer.write('\t')
+            if column is None:
+                self.buffer.write('\\N')
+            else:
+                self.buffer.write(str(column).translate(_SQL_TRANSLATION))
+        self.buffer.write('\n')
+
+
+    def copy_out(self, cur, table, columns=None):
+        """ Copy all collected data into the given table.
+        """
+        if self.buffer.tell() > 0:
+            self.buffer.seek(0)
+            cur.copy_from(self.buffer, table, columns=columns)