From 3cc28231f97b7ccd1f305baf8d7175bf8cff3d2e Mon Sep 17 00:00:00 2001
From: eelke <eelke@eelkeklein.nl>
Date: Tue, 21 Mar 2023 16:20:25 +0100
Subject: [PATCH] Support expressions as partitioning keys

---
 pglablib/catalog/PgClass.cpp          |  2 +-
 pglablib/catalog/PgClassContainer.cpp | 14 ++++++++------
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/pglablib/catalog/PgClass.cpp b/pglablib/catalog/PgClass.cpp
index 15751ff..c959dbb 100644
--- a/pglablib/catalog/PgClass.cpp
+++ b/pglablib/catalog/PgClass.cpp
@@ -292,7 +292,7 @@ QString PgClass::partitionKeyItemSql(
 ) const
 {
     if (keyItem.attNum == 0)
-        return "\"<expr>\""; // TODO add expression support for now use this to prevent a crash here because column 0 does not exist
+        return keyItem.expression;
 
     const PgAttribute *col = catalog().attributes()->findIf(
         [this, &keyItem] (const auto &att)
diff --git a/pglablib/catalog/PgClassContainer.cpp b/pglablib/catalog/PgClassContainer.cpp
index f1a3360..58e743c 100644
--- a/pglablib/catalog/PgClassContainer.cpp
+++ b/pglablib/catalog/PgClassContainer.cpp
@@ -1,8 +1,6 @@
 #include "PgClassContainer.h"
-#include "Pgsql_Connection.h"
 #include "Pgsql_Col.h"
 #include "PgDatabaseCatalog.h"
-#include "PgNamespaceContainer.h"
 #include <iterator>
 
 std::string PgClassContainer::getLoadQuery() const
@@ -18,13 +16,12 @@ std::string PgClassContainer::getLoadQuery() const
 		q += ", relhasoids ";
     if (minimumVersion(100000))
         q +=
-            ", pg_get_expr(relpartbound, oid)"
-            ", partstrat, partnatts, partattrs, partclass, partcollation"; // TODO: , partexprs";
+            ", pg_get_expr(relpartbound, pg_class.oid)"
+            ", partstrat, partnatts, partattrs, partclass, partcollation "
+            ", pg_get_expr(partexprs, partrelid) AS partexprs";
     if (minimumVersion(110000))
         q += ", partdefid";
 
-    // pg_get_expr must be called on each element in partexprs
-
     q +=
         "\nFROM pg_catalog.pg_class \n"
         "    LEFT JOIN pg_catalog.pg_description AS d ON (objoid=pg_class.oid AND objsubid=0) \n";
@@ -46,9 +43,11 @@ namespace {
         std::vector<int16_t> attNums;
         std::vector<Oid> attOpClass;
         std::vector<Oid> attCollation;
+        std::vector<QString> expressions;
 
         PartitioningKeyItems Build()
         {
+            int expr_idx = 0;
             PartitioningKeyItems result(attCount);
             for (int attIdx = 0; attIdx < attCount; ++attIdx)
             {
@@ -56,6 +55,8 @@ namespace {
                 item.attNum = attNums[attIdx];
                 item.opClass = attOpClass[attIdx];
                 item.collation = attCollation[attIdx];
+                if (item.attNum == 0)
+                    item.expression = expressions[expr_idx++];
             }
             return result;
         }
@@ -111,6 +112,7 @@ PgClass PgClassContainer::loadElem(const Pgsql::Row &row)
             col.getAsVector<int16_t>(std::back_inserter(kibuilder.attNums));
             col.getAsVector<Oid>(std::back_inserter(kibuilder.attOpClass));
             col.getAsVector<Oid>(std::back_inserter(kibuilder.attCollation));
+            col.getAsVector<QString>(std::back_inserter(kibuilder.expressions));
 
             pt.keyColumns = kibuilder.Build();
             if (minimumVersion(110000))