Examples with Explain org.h2.command.dml.Explain used on opensource projects

Example 16 with Explain

use of org.h2.command.dml.Explain in project h2database by h2database.

the class TestOptimizations method testRowId.

private void testRowId() throws SQLException {
    if (config.memory) {
        return;
    }
    Connection conn = getConnection("optimizations");
    Statement stat = conn.createStatement();
    ResultSet rs;
    stat.execute("create table test(data varchar)");
    stat.execute("select min(_rowid_ + 1) from test");
    stat.execute("insert into test(_rowid_, data) values(10, 'Hello')");
    stat.execute("insert into test(data) values('World')");
    stat.execute("insert into test(_rowid_, data) values(20, 'Hello')");
    stat.execute("merge into test(_rowid_, data) key(_rowid_) values(20, 'Hallo')");
    rs = stat.executeQuery("select _rowid_, data from test order by _rowid_");
    rs.next();
    assertEquals(10, rs.getInt(1));
    assertEquals("Hello", rs.getString(2));
    rs.next();
    assertEquals(11, rs.getInt(1));
    assertEquals("World", rs.getString(2));
    rs.next();
    assertEquals(21, rs.getInt(1));
    assertEquals("Hallo", rs.getString(2));
    assertFalse(rs.next());
    stat.execute("drop table test");
    stat.execute("create table test(id int primary key, name varchar)");
    stat.execute("insert into test values(0, 'Hello')");
    stat.execute("insert into test values(3, 'Hello')");
    stat.execute("insert into test values(2, 'Hello')");
    rs = stat.executeQuery("explain select * from test where _rowid_ = 2");
    rs.next();
    assertContains(rs.getString(1), ".tableScan: _ROWID_ =");
    rs = stat.executeQuery("explain select * from test where _rowid_ > 2");
    rs.next();
    assertContains(rs.getString(1), ".tableScan: _ROWID_ >");
    rs = stat.executeQuery("explain select * from test order by _rowid_");
    rs.next();
    assertContains(rs.getString(1), "/* index sorted */");
    rs = stat.executeQuery("select _rowid_, * from test order by _rowid_");
    rs.next();
    assertEquals(0, rs.getInt(1));
    assertEquals(0, rs.getInt(2));
    rs.next();
    assertEquals(2, rs.getInt(1));
    assertEquals(2, rs.getInt(2));
    rs.next();
    assertEquals(3, rs.getInt(1));
    assertEquals(3, rs.getInt(2));
    stat.execute("drop table test");
    conn.close();
}

Example 17 with Explain

use of org.h2.command.dml.Explain in project h2database by h2database.

the class TestOptimizations method testOrderByExpression.

private void testOrderByExpression() throws Exception {
    Connection conn = getConnection("optimizations");
    Statement stat = conn.createStatement();
    stat.execute("create table test(id int primary key, name varchar)");
    stat.execute("insert into test values(1, 'Hello'), (2, 'Hello'), (3, 'Hello')");
    ResultSet rs;
    rs = stat.executeQuery("explain select name from test where name='Hello' order by name");
    rs.next();
    String plan = rs.getString(1);
    assertContains(plan, "tableScan");
    stat.execute("drop table test");
    conn.close();
}

Example 18 with Explain

use of org.h2.command.dml.Explain in project ignite by apache.

the class GridH2TableSelfTest method checkQueryPlan.

/**
     * Check query plan to correctly select index.
     *
     * @param conn Connection.
     * @param sql Select.
     * @param search Search token in result.
     * @throws SQLException If failed.
     */
private void checkQueryPlan(Connection conn, String sql, String search) throws SQLException {
    try (Statement s = conn.createStatement()) {
        try (ResultSet r = s.executeQuery("EXPLAIN ANALYZE " + sql)) {
            assertTrue(r.next());
            String plan = r.getString(1);
            assertTrue("Execution plan for '" + sql + "' query should contain '" + search + "'", plan.contains(search));
        }
    }
}

Example 19 with Explain

use of org.h2.command.dml.Explain in project ignite by apache.

the class GridReduceQueryExecutor method createMergeTable.

/**
 * @param conn Connection.
 * @param qry Query.
 * @param explain Explain.
 * @return Table.
 * @throws IgniteCheckedException If failed.
 */
@SuppressWarnings("unchecked")
private GridMergeTable createMergeTable(JdbcConnection conn, GridCacheSqlQuery qry, boolean explain) throws IgniteCheckedException {
    try {
        Session ses = (Session) conn.getSession();
        CreateTableData data = new CreateTableData();
        data.tableName = "T___";
        data.schema = ses.getDatabase().getSchema(ses.getCurrentSchemaName());
        data.create = true;
        if (!explain) {
            LinkedHashMap<String, ?> colsMap = qry.columns();
            assert colsMap != null;
            ArrayList<Column> cols = new ArrayList<>(colsMap.size());
            for (Map.Entry<String, ?> e : colsMap.entrySet()) {
                String alias = e.getKey();
                GridSqlType t = (GridSqlType) e.getValue();
                assert !F.isEmpty(alias);
                Column c = new Column(alias, t.type(), t.precision(), t.scale(), t.displaySize());
                cols.add(c);
            }
            data.columns = cols;
        } else
            data.columns = planColumns();
        boolean sortedIndex = !F.isEmpty(qry.sortColumns());
        GridMergeTable tbl = new GridMergeTable(data);
        ArrayList<Index> idxs = new ArrayList<>(2);
        if (explain) {
            idxs.add(new GridMergeIndexUnsorted(ctx, tbl, sortedIndex ? MERGE_INDEX_SORTED : MERGE_INDEX_UNSORTED));
        } else if (sortedIndex) {
            List<GridSqlSortColumn> sortCols = (List<GridSqlSortColumn>) qry.sortColumns();
            GridMergeIndexSorted sortedMergeIdx = new GridMergeIndexSorted(ctx, tbl, MERGE_INDEX_SORTED, GridSqlSortColumn.toIndexColumns(tbl, sortCols));
            idxs.add(GridMergeTable.createScanIndex(sortedMergeIdx));
            idxs.add(sortedMergeIdx);
        } else
            idxs.add(new GridMergeIndexUnsorted(ctx, tbl, MERGE_INDEX_UNSORTED));
        tbl.indexes(idxs);
        return tbl;
    } catch (Exception e) {
        U.closeQuiet(conn);
        throw new IgniteCheckedException(e);
    }
}

Example 20 with Explain

use of org.h2.command.dml.Explain in project ignite by apache.

the class GridReduceQueryExecutor method query.

/**
 * @param schemaName Schema name.
 * @param qry Query.
 * @param keepBinary Keep binary.
 * @param enforceJoinOrder Enforce join order of tables.
 * @param timeoutMillis Timeout in milliseconds.
 * @param cancel Query cancel.
 * @param params Query parameters.
 * @param parts Partitions.
 * @param lazy Lazy execution flag.
 * @return Rows iterator.
 */
public Iterator<List<?>> query(String schemaName, final GridCacheTwoStepQuery qry, boolean keepBinary, boolean enforceJoinOrder, int timeoutMillis, GridQueryCancel cancel, Object[] params, final int[] parts, boolean lazy) {
    if (F.isEmpty(params))
        params = EMPTY_PARAMS;
    final boolean isReplicatedOnly = qry.isReplicatedOnly();
    // Fail if all caches are replicated and explicit partitions are set.
    for (int attempt = 0; ; attempt++) {
        if (attempt != 0) {
            try {
                // Wait for exchange.
                Thread.sleep(attempt * 10);
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
                throw new CacheException("Query was interrupted.", e);
            }
        }
        final long qryReqId = qryIdGen.incrementAndGet();
        final ReduceQueryRun r = new ReduceQueryRun(qryReqId, qry.originalSql(), schemaName, h2.connectionForSchema(schemaName), qry.mapQueries().size(), qry.pageSize(), U.currentTimeMillis(), cancel);
        AffinityTopologyVersion topVer = h2.readyTopologyVersion();
        // Check if topology is changed while retrying on locked topology.
        if (h2.serverTopologyChanged(topVer) && ctx.cache().context().lockedTopologyVersion(null) != null) {
            throw new CacheException(new TransactionException("Server topology is changed during query " + "execution inside a transaction. It's recommended to rollback and retry transaction."));
        }
        List<Integer> cacheIds = qry.cacheIds();
        Collection<ClusterNode> nodes;
        // Explicit partition mapping for unstable topology.
        Map<ClusterNode, IntArray> partsMap = null;
        // Explicit partitions mapping for query.
        Map<ClusterNode, IntArray> qryMap = null;
        // Partitions are not supported for queries over all replicated caches.
        if (parts != null) {
            boolean replicatedOnly = true;
            for (Integer cacheId : cacheIds) {
                if (!cacheContext(cacheId).isReplicated()) {
                    replicatedOnly = false;
                    break;
                }
            }
            if (replicatedOnly)
                throw new CacheException("Partitions are not supported for replicated caches");
        }
        if (qry.isLocal())
            nodes = singletonList(ctx.discovery().localNode());
        else {
            NodesForPartitionsResult nodesParts = nodesForPartitions(cacheIds, topVer, parts, isReplicatedOnly);
            nodes = nodesParts.nodes();
            partsMap = nodesParts.partitionsMap();
            qryMap = nodesParts.queryPartitionsMap();
            if (nodes == null)
                // Retry.
                continue;
            assert !nodes.isEmpty();
            if (isReplicatedOnly || qry.explain()) {
                ClusterNode locNode = ctx.discovery().localNode();
                // Always prefer local node if possible.
                if (nodes.contains(locNode))
                    nodes = singletonList(locNode);
                else {
                    // Select random data node to run query on a replicated data or
                    // get EXPLAIN PLAN from a single node.
                    nodes = singletonList(F.rand(nodes));
                }
            }
        }
        int tblIdx = 0;
        final boolean skipMergeTbl = !qry.explain() && qry.skipMergeTable();
        final int segmentsPerIndex = qry.explain() || isReplicatedOnly ? 1 : findFirstPartitioned(cacheIds).config().getQueryParallelism();
        int replicatedQrysCnt = 0;
        final Collection<ClusterNode> finalNodes = nodes;
        for (GridCacheSqlQuery mapQry : qry.mapQueries()) {
            GridMergeIndex idx;
            if (!skipMergeTbl) {
                GridMergeTable tbl;
                try {
                    tbl = createMergeTable(r.connection(), mapQry, qry.explain());
                } catch (IgniteCheckedException e) {
                    throw new IgniteException(e);
                }
                idx = tbl.getMergeIndex();
                fakeTable(r.connection(), tblIdx++).innerTable(tbl);
            } else
                idx = GridMergeIndexUnsorted.createDummy(ctx);
            // If the query has only replicated tables, we have to run it on a single node only.
            if (!mapQry.isPartitioned()) {
                ClusterNode node = F.rand(nodes);
                mapQry.node(node.id());
                replicatedQrysCnt++;
                // Replicated tables can have only 1 segment.
                idx.setSources(singletonList(node), 1);
            } else
                idx.setSources(nodes, segmentsPerIndex);
            idx.setPageSize(r.pageSize());
            r.indexes().add(idx);
        }
        r.latch(new CountDownLatch(isReplicatedOnly ? 1 : (r.indexes().size() - replicatedQrysCnt) * nodes.size() * segmentsPerIndex + replicatedQrysCnt));
        runs.put(qryReqId, r);
        boolean release = true;
        try {
            cancel.checkCancelled();
            if (ctx.clientDisconnected()) {
                throw new CacheException("Query was cancelled, client node disconnected.", new IgniteClientDisconnectedException(ctx.cluster().clientReconnectFuture(), "Client node disconnected."));
            }
            List<GridCacheSqlQuery> mapQrys = qry.mapQueries();
            if (qry.explain()) {
                mapQrys = new ArrayList<>(qry.mapQueries().size());
                for (GridCacheSqlQuery mapQry : qry.mapQueries()) mapQrys.add(new GridCacheSqlQuery("EXPLAIN " + mapQry.query()).parameterIndexes(mapQry.parameterIndexes()));
            }
            final boolean distributedJoins = qry.distributedJoins();
            cancel.set(new Runnable() {

                @Override
                public void run() {
                    send(finalNodes, new GridQueryCancelRequest(qryReqId), null, false);
                }
            });
            boolean retry = false;
            // Always enforce join order on map side to have consistent behavior.
            int flags = GridH2QueryRequest.FLAG_ENFORCE_JOIN_ORDER;
            if (distributedJoins)
                flags |= GridH2QueryRequest.FLAG_DISTRIBUTED_JOINS;
            if (qry.isLocal())
                flags |= GridH2QueryRequest.FLAG_IS_LOCAL;
            if (qry.explain())
                flags |= GridH2QueryRequest.FLAG_EXPLAIN;
            if (isReplicatedOnly)
                flags |= GridH2QueryRequest.FLAG_REPLICATED;
            if (lazy && mapQrys.size() == 1)
                flags |= GridH2QueryRequest.FLAG_LAZY;
            GridH2QueryRequest req = new GridH2QueryRequest().requestId(qryReqId).topologyVersion(topVer).pageSize(r.pageSize()).caches(qry.cacheIds()).tables(distributedJoins ? qry.tables() : null).partitions(convert(partsMap)).queries(mapQrys).parameters(params).flags(flags).timeout(timeoutMillis).schemaName(schemaName);
            if (send(nodes, req, parts == null ? null : new ExplicitPartitionsSpecializer(qryMap), false)) {
                awaitAllReplies(r, nodes, cancel);
                Object state = r.state();
                if (state != null) {
                    if (state instanceof CacheException) {
                        CacheException err = (CacheException) state;
                        if (err.getCause() instanceof IgniteClientDisconnectedException)
                            throw err;
                        if (wasCancelled(err))
                            // Throw correct exception.
                            throw new QueryCancelledException();
                        throw new CacheException("Failed to run map query remotely." + err.getMessage(), err);
                    }
                    if (state instanceof AffinityTopologyVersion) {
                        retry = true;
                        // If remote node asks us to retry then we have outdated full partition map.
                        h2.awaitForReadyTopologyVersion((AffinityTopologyVersion) state);
                    }
                }
            } else
                // Send failed.
                retry = true;
            Iterator<List<?>> resIter = null;
            if (!retry) {
                if (skipMergeTbl) {
                    resIter = new GridMergeIndexIterator(this, finalNodes, r, qryReqId, qry.distributedJoins());
                    release = false;
                } else {
                    cancel.checkCancelled();
                    UUID locNodeId = ctx.localNodeId();
                    H2Utils.setupConnection(r.connection(), false, enforceJoinOrder);
                    GridH2QueryContext.set(new GridH2QueryContext(locNodeId, locNodeId, qryReqId, REDUCE).pageSize(r.pageSize()).distributedJoinMode(OFF));
                    try {
                        if (qry.explain())
                            return explainPlan(r.connection(), qry, params);
                        GridCacheSqlQuery rdc = qry.reduceQuery();
                        ResultSet res = h2.executeSqlQueryWithTimer(r.connection(), rdc.query(), F.asList(rdc.parameters(params)), // The statement will cache some extra thread local objects.
                        false, timeoutMillis, cancel);
                        resIter = new H2FieldsIterator(res);
                    } finally {
                        GridH2QueryContext.clearThreadLocal();
                    }
                }
            }
            if (retry) {
                if (Thread.currentThread().isInterrupted())
                    throw new IgniteInterruptedCheckedException("Query was interrupted.");
                continue;
            }
            return new GridQueryCacheObjectsIterator(resIter, h2.objectContext(), keepBinary);
        } catch (IgniteCheckedException | RuntimeException e) {
            release = true;
            U.closeQuiet(r.connection());
            if (e instanceof CacheException) {
                if (wasCancelled((CacheException) e))
                    throw new CacheException("Failed to run reduce query locally.", new QueryCancelledException());
                throw (CacheException) e;
            }
            Throwable cause = e;
            if (e instanceof IgniteCheckedException) {
                Throwable disconnectedErr = ((IgniteCheckedException) e).getCause(IgniteClientDisconnectedException.class);
                if (disconnectedErr != null)
                    cause = disconnectedErr;
            }
            throw new CacheException("Failed to run reduce query locally.", cause);
        } finally {
            if (release) {
                releaseRemoteResources(finalNodes, r, qryReqId, qry.distributedJoins());
                if (!skipMergeTbl) {
                    for (int i = 0, mapQrys = qry.mapQueries().size(); i < mapQrys; i++) // Drop all merge tables.
                    fakeTable(null, i).innerTable(null);
                }
            }
        }
    }
}