SQL: Tweak pattern matching in SYS TABLES (#41243)

Yet another improvement to SYS TABLES on differentiating between table
types specified as '%' and '' while maintaining legacy support for null

Fix #40775

(cherry picked from commit 6dbca5e)

Author: costin

x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/parser/CommandBuilder.java

@@ -146,7 +146,7 @@ public SysTables visitSysTables(SysTablesContext ctx) {
         boolean legacyTableType = false;
         for (StringContext string : ctx.string()) {
             String value = string(string);
-            if (value != null) {
+            if (value != null && value.isEmpty() == false) {
                 // check special ODBC wildcard case
                 if (value.equals(StringUtils.SQL_WILDCARD) && ctx.string().size() == 1) {
                     // treat % as null

x-pack/plugin/sql/src/test/java/org/elasticsearch/xpack/sql/plan/logical/command/sys/SysTablesTests.java

@@ -54,7 +54,30 @@ public class SysTablesTests extends ESTestCase {
     //
     // catalog enumeration
     //
-    public void testSysTablesCatalogEnumeration() throws Exception {
+    public void testSysTablesCatalogEnumerationWithEmptyType() throws Exception {
+        executeCommand("SYS TABLES CATALOG LIKE '%' LIKE '' TYPE ''", r -> {
+            assertEquals(1, r.size());
+            assertEquals(CLUSTER_NAME, r.column(0));
+            // everything else should be null
+            for (int i = 1; i < 10; i++) {
+                assertNull(r.column(i));
+            }
+        }, index);
+    }
+
+    public void testSysTablesCatalogAllTypes() throws Exception {
+        executeCommand("SYS TABLES CATALOG LIKE '%' LIKE '' TYPE '%'", r -> {
+            assertEquals(1, r.size());
+            assertEquals(CLUSTER_NAME, r.column(0));
+            // everything else should be null
+            for (int i = 1; i < 10; i++) {
+                assertNull(r.column(i));
+            }
+        }, new IndexInfo[0]);
+    }
+
+    // when types are null, consider them equivalent to '' for compatibility reasons
+    public void testSysTablesCatalogNoTypes() throws Exception {
         executeCommand("SYS TABLES CATALOG LIKE '%' LIKE ''", r -> {
             assertEquals(1, r.size());
             assertEquals(CLUSTER_NAME, r.column(0));
@@ -65,24 +88,18 @@ public void testSysTablesCatalogEnumeration() throws Exception {
         }, index);
     }
 
+
     //
     // table types enumeration
     //
+
+    // missing type means pattern
     public void testSysTablesTypesEnumerationWoString() throws Exception {
         executeCommand("SYS TABLES CATALOG LIKE '' LIKE '' ", r -> {
             assertEquals(2, r.size());
             assertEquals("BASE TABLE", r.column(3));
             assertTrue(r.advanceRow());
             assertEquals("VIEW", r.column(3));
-        }, new IndexInfo[0]);
-    }
-
-    public void testSysTablesEnumerateTypes() throws Exception {
-        executeCommand("SYS TABLES CATALOG LIKE '' LIKE '' TYPE '%'", r -> {
-            assertEquals(2, r.size());
-            assertEquals("BASE TABLE", r.column(3));
-            assertTrue(r.advanceRow());
-            assertEquals("VIEW", r.column(3));
         }, alias, index);
     }
 
@@ -107,6 +124,13 @@ public void testSysTablesTypesEnumeration() throws Exception {
         }, new IndexInfo[0]);
     }
 
+    // when a type is specified, apply filtering
+    public void testSysTablesTypesEnumerationAllCatalogsAndSpecifiedView() throws Exception {
+        executeCommand("SYS TABLES CATALOG LIKE '%' LIKE '' TYPE 'VIEW'", r -> {
+            assertEquals(0, r.size());
+        }, new IndexInfo[0]);
+    }
+
     public void testSysTablesDifferentCatalog() throws Exception {
         executeCommand("SYS TABLES CATALOG LIKE 'foo'", r -> {
             assertEquals(0, r.size());
@@ -262,6 +286,12 @@ public void testSysTablesWithCatalogOnlyAliases() throws Exception {
         }, alias);
     }
 
+    public void testSysTablesWithEmptyCatalogOnlyAliases() throws Exception {
+        executeCommand("SYS TABLES CATALOG LIKE '' LIKE 'test' TYPE 'VIEW'", r -> {
+            assertEquals(0, r.size());
+        }, alias);
+    }
+
     public void testSysTablesWithInvalidType() throws Exception {
         executeCommand("SYS TABLES LIKE 'test' TYPE 'QUE HORA ES'", r -> {
             assertEquals(0, r.size());