Add support for index prefix lengths (MySQL/MariaDB)

SQLSchemaCompare.Core/Entities/Database/ABaseDbIndex.cs

@@ -14,6 +14,11 @@ public class ABaseDbIndex : ABaseDbConstraint
     /// <remarks>Used only by the DatabaseProvider to group the indexes and fill the ColumnDescending list</remarks>
     public bool IsDescending { get; set; }
 
+    /// <summary>
+    /// Gets or sets the length of the prefix.
+    /// </summary>
+    public long? PrefixLength { get; set; }
+
     /// <summary>
     /// Gets or sets a value indicating whether the index is included.
     /// </summary>
@@ -24,6 +29,11 @@ public class ABaseDbIndex : ABaseDbConstraint
     /// </summary>
     public List<bool> ColumnDescending { get; } = [];
 
+    /// <summary>
+    /// Gets the column prefix lengths.
+    /// </summary>
+    public List<long?> ColumnPrefixLengths { get; } = [];
+
     /// <summary>
     /// Gets the included columns.
     /// </summary>

SQLSchemaCompare.Infrastructure/DatabaseProviders/ADatabaseProvider.cs

@@ -208,6 +208,7 @@ protected TDatabase DiscoverDatabase(TDatabaseContext context, TaskInfo taskInfo
                 index.Database = db;
                 index.ColumnNames.AddRange(indexGroup.Where(x => !x.IsIncluded).OrderBy(x => x.OrdinalPosition).Select(x => x.ColumnName));
                 index.ColumnDescending.AddRange(indexGroup.Where(x => !x.IsIncluded).OrderBy(x => x.OrdinalPosition).Select(x => x.IsDescending));
+                index.ColumnPrefixLengths.AddRange(indexGroup.Where(x => !x.IsIncluded).OrderBy(x => x.OrdinalPosition).Select(x => x.PrefixLength));
                 index.IncludedColumns.AddRange(indexGroup.Where(x => x.IsIncluded).OrderBy(x => x.OrdinalPosition).Select(x => x.ColumnName));
                 db.Indexes.Add(index);
             }

SQLSchemaCompare.Infrastructure/DatabaseProviders/MySqlDatabaseProvider.cs

@@ -137,7 +137,8 @@ protected override IEnumerable<ABaseDbIndex> GetIndexes(MySqlDatabaseContext con
         query.AppendLine("       CAST(s.SEQ_IN_INDEX AS SIGNED) AS 'OrdinalPosition',");
         query.AppendLine("       CASE WHEN s.COLLATION = 'D' THEN TRUE ELSE FALSE END as 'IsDescending',");
         query.AppendLine("       s.INDEX_TYPE AS 'IndexType',");
-        query.AppendLine("       COALESCE(tc.CONSTRAINT_TYPE, 'INDEX') AS 'ConstraintType'");
+        query.AppendLine("       COALESCE(tc.CONSTRAINT_TYPE, 'INDEX') AS 'ConstraintType',");
+        query.AppendLine("       s.SUB_PART AS 'PrefixLength'");
         query.AppendLine("FROM INFORMATION_SCHEMA.STATISTICS s");
         query.AppendLine("LEFT OUTER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS tc");
         query.AppendLine("  ON tc.table_name = s.table_name AND tc.table_schema = s.table_schema AND tc.constraint_name = s.index_name");

SQLSchemaCompare.Infrastructure/SqlScripters/MySqlScripter.cs

@@ -291,12 +291,19 @@ protected override string ScriptCreateIndex(ABaseDbIndex index)
         var scriptOrder = index.ColumnDescending.Any(x => x);
         var columnList = index.ColumnNames.Select((x, i) =>
         {
+            var column = $"{this.ScriptHelper.ScriptObjectName(x)}";
+
+            if (indexMySql.IndexType == "BTREE" && index.ColumnPrefixLengths[i] != null)
+            {
+                column += $"({index.ColumnPrefixLengths[i]})";
+            }
+
             if (scriptOrder)
             {
-                return $"{this.ScriptHelper.ScriptObjectName(x)} {(index.ColumnDescending[i] ? "DESC" : "ASC")}";
+                column += $" {(index.ColumnDescending[i] ? "DESC" : "ASC")}";
             }
 
-            return $"{this.ScriptHelper.ScriptObjectName(x)}";
+            return column;
         });
 
         sb.Append("CREATE ");

SQLSchemaCompare.Test/Datasources/sakila-schema-mariadb.sql

@@ -25,6 +25,7 @@ CREATE TABLE actor (
   last_update TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
   deleted BIT(1) NOT NULL DEFAULT b'0',
   PRIMARY KEY  (actor_id),
+  KEY idx_actor_name (first_name(10), last_name(15)),
   KEY idx_actor_last_name (last_name)
 )ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
 

SQLSchemaCompare.Test/Datasources/sakila-schema-mysql.sql

@@ -23,7 +23,9 @@ CREATE TABLE actor (
   first_name VARCHAR(45) NOT NULL,
   last_name VARCHAR(45) NOT NULL,
   last_update TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
+  deleted BIT(1) NOT NULL DEFAULT b'0',
   PRIMARY KEY  (actor_id),
+  KEY idx_actor_name (first_name(10), last_name(15)),
   KEY idx_actor_last_name (last_name)
 )ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;