#1468 - ENH: Add built-in DDL generation for Postgres table partitioning (by day, week, month and year) (#1469)

src/main/java/io/ebean/config/dbplatform/DatabasePlatform.java

@@ -2,6 +2,7 @@ package io.ebean.config.dbplatform;
 
 import io.ebean.BackgroundExecutor;
 import io.ebean.Query;
+import io.ebean.annotation.PartitionMode;
 import io.ebean.annotation.PersistBatch;
 import io.ebean.annotation.Platform;
 import io.ebean.config.CustomDbTypeMapping;
@@ -706,6 +707,20 @@ public class DatabasePlatform {
     }
   }
 
+  /**
+   * Return true if partitions exist for the given table.
+   */
+  public boolean tablePartitionsExist(Connection connection, String table) throws SQLException {
+    return true;
+  }
+
+  /**
+   * Return the SQL to create an initial partition for the given table.
+   */
+  public String tablePartitionInit(String tableName, PartitionMode mode, String property, String singlePrimaryKey) {
+    return null;
+  }
+
   /**
    * Escapes the like string for this DB-Platform
    */

src/main/java/io/ebean/config/dbplatform/postgres/PostgresPlatform.java

@@ -2,6 +2,7 @@ package io.ebean.config.dbplatform.postgres;
 
 import io.ebean.BackgroundExecutor;
 import io.ebean.Query;
+import io.ebean.annotation.PartitionMode;
 import io.ebean.annotation.Platform;
 import io.ebean.config.dbplatform.DatabasePlatform;
 import io.ebean.config.dbplatform.DbPlatformType;
@@ -11,6 +12,10 @@ import io.ebean.config.dbplatform.PlatformIdGenerator;
 import io.ebean.config.dbplatform.SqlErrorCodes;
 
 import javax.sql.DataSource;
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
 import java.sql.Types;
 
 /**
@@ -116,4 +121,31 @@ public class PostgresPlatform extends DatabasePlatform {
         return sql + " for update";
     }
   }
+
+  @Override
+  public boolean tablePartitionsExist(Connection connection, String table) throws SQLException {
+
+    try (PreparedStatement statement = connection.prepareStatement("select count(*) from pg_inherits i WHERE  i.inhparent = ?::regclass")) {
+      statement.setString(1, table);
+      try (ResultSet resultSet = statement.executeQuery()) {
+        return resultSet.next() && resultSet.getInt(1) > 0;
+      }
+    }
+  }
+
+  /**
+   * Return SQL using built in partition helper functions to create some initial partitions.
+   *
+   * Only use this if extra-dll doesn't have some initial partitions defined (which it should).
+   */
+  public String tablePartitionInit(String tableName, PartitionMode mode, String property, String pkey) {
+    if (property == null) {
+      property = "";
+    }
+    if (pkey == null) {
+      pkey = "";
+    }
+    return "select partition('" + mode.name().toLowerCase() + "','" + tableName + "','" + pkey + "','" + property + "',1);";
+  }
+
 }

src/main/java/io/ebean/dbmigration/DbMigration.java

@@ -98,6 +98,11 @@ public interface DbMigration {
    */
   void setIncludeGeneratedFileComment(boolean includeGeneratedFileComment);
 
+  /**
+   * Set this to false to exclude the builtin support for table partitioning (with @DbPartition).
+   */
+  void setIncludeBuiltInPartitioning(boolean includeBuiltInPartitioning);
+
   /**
    * Set the header that is included in the generated DDL script.
    */

src/main/java/io/ebeaninternal/dbmigration/DdlGenerator.java

@@ -1,11 +1,14 @@
 package io.ebeaninternal.dbmigration;
 
 import io.ebean.config.ServerConfig;
+import io.ebean.config.dbplatform.DatabasePlatform;
 import io.ebean.migration.ddl.DdlRunner;
 import io.ebean.util.JdbcClose;
 import io.ebeaninternal.api.SpiEbeanServer;
 import io.ebeaninternal.dbmigration.model.CurrentModel;
+import io.ebeaninternal.dbmigration.model.MTable;
 import io.ebeaninternal.extraddl.model.ExtraDdlXmlReader;
+import io.ebeaninternal.server.deploy.PartitionMeta;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -180,10 +183,50 @@ public class DdlGenerator {
 
     String ignoreExtraDdl = System.getProperty("ebean.ignoreExtraDdl");
     if (!"true".equalsIgnoreCase(ignoreExtraDdl) && jaxbPresent) {
+      if (currentModel.isTablePartitioning()) {
+        String extraPartitioning = ExtraDdlXmlReader.buildPartitioning(server.getDatabasePlatform().getName());
+        if (extraPartitioning != null && !extraPartitioning.isEmpty()) {
+          runScript(connection, false, extraPartitioning, "builtin-partitioning-dll");
+        }
+      }
+
       String extraApply = ExtraDdlXmlReader.buildExtra(server.getDatabasePlatform().getName(), false);
       if (extraApply != null) {
         runScript(connection, false, extraApply, "extra-dll");
       }
+
+      if (currentModel.isTablePartitioning()) {
+        checkInitialTablePartitions(connection);
+      }
+    }
+  }
+
+  /**
+   * Check if table partitions exist and if not create some. The expectation is that
+   * extra-dll.xml should have some partition initialisation but this helps people get going.
+   */
+  private void checkInitialTablePartitions(Connection connection) {
+
+    DatabasePlatform databasePlatform = server.getDatabasePlatform();
+    try {
+      StringBuilder sb = new StringBuilder();
+      for (MTable table : currentModel.getPartitionedTables()) {
+        String tableName = table.getName();
+        if (!databasePlatform.tablePartitionsExist(connection, tableName)) {
+          log.info("No table partitions for table {}", tableName);
+          PartitionMeta meta = table.getPartitionMeta();
+          String initPart = databasePlatform.tablePartitionInit(tableName, meta.getMode(), meta.getProperty(), table.singlePrimaryKey());
+          sb.append(initPart).append("\n");
+        }
+      }
+
+      String initialPartitionSql = sb.toString();
+      if (!initialPartitionSql.isEmpty()) {
+        runScript(connection, false, initialPartitionSql, "initial table partitions");
+      }
+
+    } catch (SQLException e) {
+      log.error("Error checking initial table partitions", e);
     }
   }
 

src/main/java/io/ebeaninternal/dbmigration/DefaultDbMigration.java

@@ -100,6 +100,8 @@ public class DefaultDbMigration implements DbMigration {
   protected String name;
   protected String generatePendingDrop;
 
+  protected boolean includeBuiltInPartitioning = true;
+
   /**
    * Create for offline migration generation.
    */
@@ -181,6 +183,11 @@ public class DefaultDbMigration implements DbMigration {
     this.includeGeneratedFileComment = includeGeneratedFileComment;
   }
 
+  @Override
+  public void setIncludeBuiltInPartitioning(boolean includeBuiltInPartitioning) {
+    this.includeBuiltInPartitioning = includeBuiltInPartitioning;
+  }
+
   @Override
   public void setHeader(String header) {
     this.header = header;
@@ -279,7 +286,7 @@ public class DefaultDbMigration implements DbMigration {
     try {
       Request request = createRequest();
       if (platforms.isEmpty()) {
-        generateExtraDdl(request.migrationDir, databasePlatform);
+        generateExtraDdl(request.migrationDir, databasePlatform, request.isTablePartitioning());
       }
 
       String pendingVersion = generatePendingDrop();
@@ -314,24 +321,27 @@ public class DefaultDbMigration implements DbMigration {
    * migration runner.
    * </p>
    */
-  private void generateExtraDdl(File migrationDir, DatabasePlatform dbPlatform) throws IOException {
+  private void generateExtraDdl(File migrationDir, DatabasePlatform dbPlatform, boolean tablePartitioning) throws IOException {
 
     if (dbPlatform != null) {
-      generateExtraDdl(migrationDir, dbPlatform, ExtraDdlXmlReader.readBuiltin());
-      generateExtraDdl(migrationDir, dbPlatform, ExtraDdlXmlReader.read());
+      if (tablePartitioning && includeBuiltInPartitioning) {
+        generateExtraDdlFor(migrationDir, dbPlatform, ExtraDdlXmlReader.readBuiltinTablePartitioning());
+      }
+      generateExtraDdlFor(migrationDir, dbPlatform, ExtraDdlXmlReader.readBuiltin());
+      generateExtraDdlFor(migrationDir, dbPlatform, ExtraDdlXmlReader.read());
     }
   }
 
-  private void generateExtraDdl(File migrationDir, DatabasePlatform dbPlatform, ExtraDdl extraDdl) throws IOException {
+  private void generateExtraDdlFor(File migrationDir, DatabasePlatform dbPlatform, ExtraDdl extraDdl) throws IOException {
     if (extraDdl != null) {
       List<DdlScript> ddlScript = extraDdl.getDdlScript();
       for (DdlScript script : ddlScript) {
         if (!script.isDrop() && ExtraDdlXmlReader.matchPlatform(dbPlatform.getName(), script.getPlatforms())) {
-            writeExtraDdl(migrationDir, script);
-          }
+          writeExtraDdl(migrationDir, script);
         }
       }
     }
+  }
 
   /**
    * Write (or override) the "repeatable" migration script.
@@ -349,8 +359,6 @@ public class DefaultDbMigration implements DbMigration {
     }
   }
 
-
-
   private String repeatableMigrationName(boolean init, String scriptName) {
     StringBuilder sb = new StringBuilder();
     if (init) {
@@ -421,6 +429,10 @@ public class DefaultDbMigration implements DbMigration {
       this.current = currentModel.read();
     }
 
+    boolean isTablePartitioning() {
+      return current.isTablePartitioning();
+    }
+
     /**
      * Return the migration for the pending drops for a given version.
      */
@@ -528,7 +540,7 @@ public class DefaultDbMigration implements DbMigration {
       File subPath = platformWriter.subPath(writePath, pair.prefix);
       platformWriter.processMigration(dbMigration, platformBuffer, subPath, fullVersion);
 
-      generateExtraDdl(subPath, pair.platform);
+      generateExtraDdl(subPath, pair.platform, currentModel.isTablePartitioning());
     }
   }
 

src/main/java/io/ebeaninternal/dbmigration/model/CurrentModel.java

@@ -60,6 +60,20 @@ public class CurrentModel {
     this.platformTypes = platformTypes;
   }
 
+  /**
+   * Return true if the model contains tables that are partitioned.
+   */
+  public boolean isTablePartitioning() {
+    return model.isTablePartitioning();
+  }
+
+  /**
+   * Return the tables that have partitioning.
+   */
+  public List<MTable> getPartitionedTables() {
+    return model.getPartitionedTables();
+  }
+
   private static DbConstraintNaming.MaxLength maxLength(SpiEbeanServer server, DbConstraintNaming naming) {
 
     if (naming.getMaxLength() != null) {
@@ -116,17 +130,7 @@ public class CurrentModel {
       ddl.append(header).append('\n');
     }
 
-    ExtraDdl extraDdl = ExtraDdlXmlReader.readBuiltin();
-    if (extraDdl != null) {
-      List<DdlScript> ddlScript = extraDdl.getDdlScript();
-      for (DdlScript script : ddlScript) {
-        if (script.isInit() && ExtraDdlXmlReader.matchPlatform(server.getDatabasePlatform().getName(), script.getPlatforms())) {
-          ddl.append("-- init script " + script.getName()).append('\n');
-          ddl.append(script.getValue());
-        }
-      }
-    }
-
+    addExtraDdl(ddl, ExtraDdlXmlReader.readBuiltin(), "-- init script ");
 
     ddl.append(write.apply().getBuffer());
     ddl.append(write.applyForeignKeys().getBuffer());
@@ -136,6 +140,18 @@ public class CurrentModel {
     return ddl.toString();
   }
 
+  private void addExtraDdl(StringBuilder ddl, ExtraDdl extraDdl, String prefix) {
+    if (extraDdl != null) {
+      List<DdlScript> ddlScript = extraDdl.getDdlScript();
+      for (DdlScript script : ddlScript) {
+        if (script.isInit() && ExtraDdlXmlReader.matchPlatform(server.getDatabasePlatform().getName(), script.getPlatforms())) {
+          ddl.append(prefix + script.getName()).append('\n');
+          ddl.append(script.getValue());
+        }
+      }
+    }
+  }
+
   /**
    * Return the 'Drop' DDL.
    */

src/main/java/io/ebeaninternal/dbmigration/model/MTable.java

@@ -434,6 +434,13 @@ public class MTable {
     return partitionMeta != null;
   }
 
+  /**
+   * Return the partition meta for this table.
+   */
+  public PartitionMeta getPartitionMeta() {
+    return partitionMeta;
+  }
+
   public void setPkName(String pkName) {
     this.pkName = pkName;
   }
@@ -546,6 +553,17 @@ public class MTable {
     return pk;
   }
 
+  /**
+   * Return the primary key column if it is a simple primary key.
+   */
+  public String singlePrimaryKey() {
+    List<MColumn> columns = primaryKeyColumns();
+    if (columns.size() == 1) {
+      return columns.get(0).getName();
+    }
+    return null;
+  }
+
   private void checkTableName(String tableName) {
     if (!name.equals(tableName)) {
       throw new IllegalArgumentException("addColumn tableName [" + tableName + "] does not match [" + name + "]");

src/main/java/io/ebeaninternal/dbmigration/model/ModelContainer.java

@@ -19,6 +19,7 @@ import io.ebeaninternal.dbmigration.migration.DropTable;
 import io.ebeaninternal.dbmigration.migration.Migration;
 import io.ebeaninternal.dbmigration.migration.Sql;
 
+import java.util.ArrayList;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
@@ -43,9 +44,25 @@ public class ModelContainer {
 
   private final PendingDrops pendingDrops = new PendingDrops();
 
+  private final List<MTable> partitionedTables = new ArrayList<>();
+
   public ModelContainer() {
   }
 
+  /**
+   * Return true if the model contains tables that are partitioned.
+   */
+  public boolean isTablePartitioning() {
+    return !partitionedTables.isEmpty();
+  }
+
+  /**
+   * Return the list of partitioned tables.
+   */
+  public List<MTable> getPartitionedTables() {
+    return partitionedTables;
+  }
+
   /**
    * Adjust the FK references on all the draft tables.
    */
@@ -300,6 +317,9 @@ public class ModelContainer {
    * Add a table (typically from reading EbeanServer meta data).
    */
   public MTable addTable(MTable table) {
+    if (table.isPartitioned()) {
+      partitionedTables.add(table);
+    }
     return tables.put(table.getName(), table);
   }
 

src/main/java/io/ebeaninternal/extraddl/model/ExtraDdlXmlReader.java

@@ -26,9 +26,22 @@ public class ExtraDdlXmlReader {
   public static String buildExtra(String platformName, boolean drops) {
 
     ExtraDdl read = ExtraDdlXmlReader.read("/extra-ddl.xml");
+    return buildExtra(platformName, drops, read);
+  }
+
+  /**
+   * Return any extra DDL for supporting partitioning given the database platform.
+   */
+  public static String buildPartitioning(String platformName) {
+    return buildExtra(platformName, false, readBuiltinTablePartitioning());
+  }
+
+  private static String buildExtra(String platformName, boolean drops, ExtraDdl read) {
+
     if (read == null) {
       return null;
     }
+
     StringBuilder sb = new StringBuilder(300);
     for (DdlScript script : read.getDdlScript()) {
       if (script.isDrop() == drops && matchPlatform(platformName, script.getPlatforms())) {
@@ -90,6 +103,13 @@ public class ExtraDdlXmlReader {
     return read("/io/ebeaninternal/dbmigration/builtin-extra-ddl.xml");
   }
 
+  /**
+   * Read the builtin extra ddl to support table partitioning.
+   */
+  public static ExtraDdl readBuiltinTablePartitioning() {
+    return read("/io/ebeaninternal/dbmigration/builtin-extra-ddl-partitioning.xml");
+  }
+
   /**
    * Read the extra ddl.
    */