Avoid dumping COLLATE default for const clause

.github/composite-actions/build-modified-postgres/action.yml

@@ -3,7 +3,7 @@ inputs:
   engine_branch:
     description: 'Engine Branch'
     required: no
-    default: 'latest'
+    default: 'jira-babel-3895-2x'
   install_dir:
     description: 'Engine install directory'
     required: no
@@ -23,14 +23,14 @@ runs:
 
         if [[ $GITHUB_EVENT_NAME == "pull_request" ]]; then
           if [[ ${{inputs.engine_branch}} == "latest" ]]; then
-            ENGINE_BRANCH=$GITHUB_HEAD_REF
+            ENGINE_BRANCH='jira-babel-3895-2x'
           else
             ENGINE_BRANCH=${{inputs.engine_branch}}
           fi            
           REPOSITORY_OWNER=$HEAD_OWNER
         else
           if [[ ${{inputs.engine_branch}} == "latest" ]]; then
-            ENGINE_BRANCH=$GITHUB_REF_NAME
+            ENGINE_BRANCH='jira-babel-3895-2x'
           else
             ENGINE_BRANCH=${{inputs.engine_branch}}
           fi

.github/scripts/clone_engine_repo

@@ -78,6 +78,10 @@ else
             BRANCH_OPTION=''
         fi
     fi
+    if [ "$BRANCH" = "jira-babel-3895-2x" ]; then
+            BASE_URL=https://github.com/amazon-aurora/postgresql_modified_for_babelfish
+            BRANCH_OPTION="--branch $BRANCH"
+    fi
 fi
 GIT_URL=${BASE_URL}.git
 

contrib/babelfishpg_common/src/babelfishpg_common.c

@@ -10,6 +10,7 @@
 #include "parser/parse_target.h"
 #include "parser/scansup.h"  /* downcase_identifier */
 #include "utils/guc.h"
+#include "utils/ruleutils.h"
 
 #include "babelfishpg_common.h"
 #include "collation.h"
@@ -131,6 +132,8 @@ _PG_init(void)
 
 	prev_PreCreateCollation_hook = PreCreateCollation_hook;
 	PreCreateCollation_hook = BabelfishPreCreateCollation_hook;
+
+	get_tsql_const_collation_hook = get_tsql_const_collation;
 }
 void
 _PG_fini(void)
@@ -141,6 +144,7 @@ _PG_fini(void)
 	CLUSTER_COLLATION_OID_hook = prev_CLUSTER_COLLATION_OID_hook;
 	TranslateCollation_hook = prev_TranslateCollation_hook;
 	PreCreateCollation_hook = prev_PreCreateCollation_hook;
+	get_tsql_const_collation_hook = NULL;
 }
 
 common_utility_plugin *

contrib/babelfishpg_common/src/collation.c

@@ -1517,4 +1517,35 @@ babelfish_update_server_collation_name(PG_FUNCTION_ARGS)
 	server_collation_name = pstrdup(babelfish_restored_server_collation_name);
 	MemoryContextSwitchTo(oldContext);
 	PG_RETURN_VOID();
+}
+
+
+/*
+ * get_tsql_const_collation - determines whether collation needs to be dumped or not
+ * for collatable data types such as varchar, char, nvarchar, nchar, etc for Const clause.
+ * 
+ * This would be required to handle clause like default clause, check constraints, etc in case 
+ * of if the server is already upgraded to version > 14.6 (Babelfish v2.3.0) via minor Version 
+ * Upgrade and Major Version Upgrade from version > 14.6 (Babelfish v2.3.0) to 15.1 or later 
+ * is being performed because the default collation of collatable data types is fixed during Babelfish 
+ * v2.3.0 ie., default collation would now be same as T-SQL collation which was DEFAULT_COLLATION_OID
+ * previously. And all the existing const clause like default clause and check constraint clause might 
+ * still be pointing to PG's default collation. So this function will help to avoid dumping COLLATE 
+ * clause in such cases.
+ */
+bool
+get_tsql_const_collation(Const *constval) {
+    Oid typid = constval->consttype;
+    Oid typcollation = get_typcollation(typid);
+
+	if (typcollation != DEFAULT_COLLATION_OID &&
+		(is_tsql_nvarchar_datatype(typid) ||
+		 is_tsql_varchar_datatype(typid) ||
+		 is_tsql_bpchar_datatype(typid) ||
+		 is_tsql_nchar_datatype(typid)))
+	{
+		return false;
+	}
+
+	return true;
 }

contrib/babelfishpg_common/src/collation.h

@@ -155,3 +155,5 @@ BabelfishPreCreateCollation_hook(
 
 extern TranslateCollation_hook_type prev_TranslateCollation_hook;
 extern PreCreateCollation_hook_type prev_PreCreateCollation_hook;
+
+extern bool get_tsql_const_collation(Const *constval);