Support `postgresql_concurrently` on index dropping.

Also adds version detection so that DROP INDEX CONCURRENTLY
only renders if the Postgresql version is 9.2 or higher;
for CREATE INDEX CONCURRENTLY, version detection is added
to allow the phrase to omit if the Postgresql version is
less than 8.2.

Co-authored-by: Mike Bayer <mike_mp@zzzcomputing.com>
Change-Id: I597287e0ebbbe256c957a3579b58ace6848ab4f4
Pull-request: https://bitbucket.org/zzzeek/sqlalchemy/pull-requests/84

1 files changed, 26 insertions, 0 deletions

diff --git a/test/dialect/postgresql/test_compiler.py b/test/dialect/postgresql/test_compiler.py
index c8dc9582a..f85ff2682 100644
--- a/test/dialect/postgresql/test_compiler.py
+++ b/test/dialect/postgresql/test_compiler.py
@@ -485,6 +485,32 @@ class CompileTest(fixtures.TestBase, AssertsCompiledSQL):
             "CREATE INDEX CONCURRENTLY test_idx1 ON testtbl (data)"
         )
 
+        dialect_8_1 = postgresql.dialect()
+        dialect_8_1._supports_create_index_concurrently = False
+        self.assert_compile(
+            schema.CreateIndex(idx1),
+            "CREATE INDEX test_idx1 ON testtbl (data)",
+            dialect=dialect_8_1
+        )
+
+    def test_drop_index_concurrently(self):
+        m = MetaData()
+        tbl = Table('testtbl', m, Column('data', Integer))
+
+        idx1 = Index('test_idx1', tbl.c.data, postgresql_concurrently=True)
+        self.assert_compile(
+            schema.DropIndex(idx1),
+            "DROP INDEX CONCURRENTLY test_idx1"
+        )
+
+        dialect_9_1 = postgresql.dialect()
+        dialect_9_1._supports_drop_index_concurrently = False
+        self.assert_compile(
+            schema.DropIndex(idx1),
+            "DROP INDEX test_idx1",
+            dialect=dialect_9_1
+        )
+
     def test_exclude_constraint_min(self):
         m = MetaData()
         tbl = Table('testtbl', m,