Added lazy result sets for SCAN queries (#67)

Author: alex268

jdbc/src/main/java/tech/ydb/jdbc/YdbConnection.java

@@ -2,89 +2,19 @@
 
 import java.sql.Connection;
 import java.sql.SQLException;
-import java.util.List;
 
 import javax.annotation.Nullable;
 
 import tech.ydb.jdbc.context.YdbContext;
-import tech.ydb.jdbc.context.YdbValidator;
-import tech.ydb.jdbc.query.ExplainedQuery;
-import tech.ydb.jdbc.query.YdbQuery;
-import tech.ydb.table.query.Params;
-import tech.ydb.table.result.ResultSetReader;
-import tech.ydb.table.values.ListValue;
+import tech.ydb.jdbc.context.YdbExecutor;
 
 public interface YdbConnection extends Connection {
-    /**
-     * Return current YDB transaction, if exists
-     *
-     * @return YDB transaction ID or null, if no transaction started
-     */
     @Nullable
-    String getYdbTxId();
-
+    String getYdbTxId() throws SQLException;
 
     YdbContext getCtx();
 
-    /**
-     * Explicitly execute query as a schema query
-     *
-     * @param yql query (DDL) to execute
-     * @param validator handler for logging and warnings
-     * @throws SQLException if query cannot be executed
-     */
-    void executeSchemeQuery(String yql, YdbValidator validator) throws SQLException;
-
-    /**
-     * Explicitly execute bulk upsert to the table
-     *
-     * @param yql description of request
-     * @param tablePath path to table
-     * @param validator handler for logging and warnings
-     * @param rows bulk rows
-     * @throws SQLException if query cannot be executed
-     */
-    void executeBulkUpsertQuery(String yql, String tablePath, YdbValidator validator, ListValue rows)
-            throws SQLException;
-
-    /**
-     * Explicitly execute query as a data query
-     *
-     * @param query query to execute
-     * @param yql YQL text to execute
-     * @param params parameters for query
-     * @param timeout timeout of operation
-     * @param keepInCache flag to store query in server-side cache
-     * @param validator handler for logging and warnings
-     * @return list of result set
-     * @throws SQLException if query cannot be executed
-     */
-    List<ResultSetReader> executeDataQuery(YdbQuery query, String yql, YdbValidator validator,
-            int timeout, boolean keepInCache, Params params) throws SQLException;
-
-    /**
-     * Explicitly execute query as a scan query
-     *
-     * @param query query to execute
-     * @param yql YQL text to execute
-     * @param params parameters for query
-     * @param validator handler for logging and warnings
-     * @return single result set with rows
-     * @throws SQLException if query cannot be executed
-     */
-    ResultSetReader executeScanQuery(YdbQuery query, String yql, YdbValidator validator, Params params)
-            throws SQLException;
-
-    /**
-     * Explicitly explain this query
-     *
-     * @param yql query to explain
-     * @param validator handler for logging and warnings
-     * @return list of result set of two string columns: {@link YdbConst#EXPLAIN_COLUMN_AST}
-     * and {@link YdbConst#EXPLAIN_COLUMN_PLAN}
-     * @throws SQLException if query cannot be explained
-     */
-    ExplainedQuery executeExplainQuery(String yql, YdbValidator validator) throws SQLException;
+    YdbExecutor getExecutor();
 
     @Override
     YdbDatabaseMetaData getMetaData() throws SQLException;

jdbc/src/main/java/tech/ydb/jdbc/YdbResultSet.java

@@ -2,22 +2,10 @@
 
 import java.sql.ResultSet;
 import java.sql.SQLException;
-import java.util.Optional;
 
-import tech.ydb.table.result.ResultSetReader;
 import tech.ydb.table.values.Value;
 
 public interface YdbResultSet extends ResultSet {
-
-    /**
-     * Return YDB result set reader for direct processing
-     *
-     * @return YDB original result set reader
-     */
-    ResultSetReader getYdbResultSetReader();
-
-    //
-
     /**
      * Returns native YDB value, extracted from optional value.
      * Please note that this method will create value object for each method call.
@@ -26,7 +14,7 @@ public interface YdbResultSet extends ResultSet {
      * @return value if available; return empty if value is optional and no value provided
      * @throws SQLException if column cannot be read
      */
-    Optional<Value<?>> getNativeColumn(int columnIndex) throws SQLException;
+    Value<?> getNativeColumn(int columnIndex) throws SQLException;
 
     /**
      * Return native YDB value.
@@ -36,7 +24,7 @@ public interface YdbResultSet extends ResultSet {
      * @return value if available
      * @throws SQLException if column cannot be read
      */
-    Optional<Value<?>> getNativeColumn(String columnLabel) throws SQLException;
+    Value<?> getNativeColumn(String columnLabel) throws SQLException;
 
     //
 

jdbc/src/main/java/tech/ydb/jdbc/YdbResultSetMetaData.java

@@ -2,9 +2,6 @@
 
 import java.sql.ResultSetMetaData;
 import java.sql.SQLException;
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.List;
 
 import tech.ydb.table.values.Type;
 
@@ -15,31 +12,7 @@ public interface YdbResultSetMetaData extends ResultSetMetaData {
      *
      * @param column column, 1..N
      * @return YDB type
+     * @throws java.sql.SQLException
      */
     Type getYdbType(int column) throws SQLException;
-
-    /**
-     * Returns column index by it's name, could be useful sometimes; basically because in YDB you should always
-     * work with names (columns or parameters), indexes are just internal details
-     *
-     * @param columnName column name to find
-     * @return column (1..N)
-     * @throws SQLException if column is unknown
-     */
-    int getColumnIndex(String columnName) throws SQLException;
-
-    /**
-     * Returns all column names
-     *
-     * @return column names
-     * @throws SQLException in case something bad happens
-     */
-    default Collection<String> getColumnNames() throws SQLException {
-        int count = getColumnCount();
-        List<String> columns = new ArrayList<>(count);
-        for (int i = 0; i < count; i++) {
-            columns.add(getColumnName(i + 1));
-        }
-        return columns;
-    }
 }

jdbc/src/main/java/tech/ydb/jdbc/YdbStatement.java

@@ -3,6 +3,8 @@
 import java.sql.SQLException;
 import java.sql.Statement;
 
+import tech.ydb.jdbc.context.YdbValidator;
+
 public interface YdbStatement extends Statement {
     /**
      * Explicitly execute query as a schema query
@@ -31,16 +33,7 @@ public interface YdbStatement extends Statement {
      */
     YdbResultSet executeExplainQuery(String sql) throws SQLException;
 
-    /**
-     * Cant return previous results sets after {@link #getMoreResults()} traverse,
-     * in case previous rows were not removed by providing {@link Statement#CLOSE_ALL_RESULTS}
-     * or {@link Statement#CLOSE_CURRENT_RESULT}
-     *
-     * @param resultSetIndex index
-     * @return optional result (if traversed before) with {@link #getMoreResults()}
-     * @throws SQLException when trying to get result set on closed connection
-     */
-    YdbResultSet getResultSetAt(int resultSetIndex) throws SQLException;
+    YdbValidator getValidator();
 
     @Override
     YdbResultSet executeQuery(String sql) throws SQLException;
@@ -51,4 +44,5 @@ public interface YdbStatement extends Statement {
     @Override
     YdbConnection getConnection() throws SQLException;
 
+    void waitReady() throws SQLException;
 }

jdbc/src/main/java/tech/ydb/jdbc/common/ColumnInfo.java

@@ -0,0 +1,79 @@
+package tech.ydb.jdbc.common;
+
+import tech.ydb.table.result.ResultSetReader;
+import tech.ydb.table.values.PrimitiveType;
+import tech.ydb.table.values.Type;
+
+/**
+ *
+ * @author Aleksandr Gorshenin
+ */
+public class ColumnInfo {
+    private final String name;
+    private final Type ydbType;
+    private final MappingGetters.SqlType sqlType;
+    private final MappingGetters.Getters getters;
+
+    private final boolean isOptional;
+    private final boolean isTimestamp;
+    private final boolean isNumber;
+    private final boolean isNull;
+
+    public ColumnInfo(String name, Type type) {
+        this.name = name;
+
+        TypeDescription desc = TypeDescription.of(type);
+        this.sqlType = desc.sqlType();
+        this.getters = desc.getters();
+        this.isOptional = desc.isOptional();
+        this.ydbType = desc.ydbType();
+
+        this.isTimestamp = ydbType == PrimitiveType.Timestamp;
+        this.isNumber = ydbType == PrimitiveType.Int8 || ydbType == PrimitiveType.Uint8
+                || ydbType == PrimitiveType.Int16 || ydbType == PrimitiveType.Uint16
+                || ydbType == PrimitiveType.Int32 || ydbType == PrimitiveType.Uint32
+                || ydbType == PrimitiveType.Int64 || ydbType == PrimitiveType.Uint64;
+        this.isNull = ydbType.getKind() == Type.Kind.NULL || ydbType.getKind() == Type.Kind.VOID;
+    }
+
+    public String getName() {
+        return this.name;
+    }
+
+    public Type getYdbType() {
+        return this.ydbType;
+    }
+
+    public boolean isNull() {
+        return isNull;
+    }
+
+    public boolean isTimestamp() {
+        return isTimestamp;
+    }
+
+    public boolean isNumber() {
+        return isNumber;
+    }
+
+    public boolean isOptional() {
+        return isOptional;
+    }
+
+    public MappingGetters.SqlType getSqlType() {
+        return this.sqlType;
+    }
+
+    public MappingGetters.Getters getGetters() {
+        return this.getters;
+    }
+
+    public static ColumnInfo[] fromResultSetReader(ResultSetReader rsr) {
+        ColumnInfo[] columns = new ColumnInfo[rsr.getColumnCount()];
+        for (int idx = 0; idx < rsr.getColumnCount(); idx += 1) {
+            columns[idx] = new ColumnInfo(rsr.getColumnName(idx), rsr.getColumnType(idx));
+        }
+        return columns;
+    }
+
+}