jon-wei commented on code in PR #15469: URL: https://github.com/apache/druid/pull/15469#discussion_r1419713185
########## extensions-core/druid-catalog/src/main/java/org/apache/druid/catalog/sql/LiveCatalogResolver.java: ########## @@ -0,0 +1,211 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ + +package org.apache.druid.catalog.sql; + +import com.google.common.collect.ImmutableSet; +import org.apache.druid.catalog.model.ColumnSpec; +import org.apache.druid.catalog.model.Columns; +import org.apache.druid.catalog.model.ResolvedTable; +import org.apache.druid.catalog.model.TableId; +import org.apache.druid.catalog.model.facade.DatasourceFacade; +import org.apache.druid.catalog.model.table.DatasourceDefn; +import org.apache.druid.catalog.sync.MetadataCatalog; +import org.apache.druid.query.TableDataSource; +import org.apache.druid.segment.column.ColumnType; +import org.apache.druid.segment.column.RowSignature; +import org.apache.druid.sql.calcite.planner.CatalogResolver; +import org.apache.druid.sql.calcite.table.DatasourceTable; +import org.apache.druid.sql.calcite.table.DatasourceTable.EffectiveColumnMetadata; +import org.apache.druid.sql.calcite.table.DatasourceTable.EffectiveMetadata; +import org.apache.druid.sql.calcite.table.DatasourceTable.PhysicalDatasourceMetadata; +import org.apache.druid.sql.calcite.table.DruidTable; + +import javax.inject.Inject; + +import java.util.HashMap; +import java.util.HashSet; +import java.util.Map; +import java.util.Set; + +public class LiveCatalogResolver implements CatalogResolver +{ + private final MetadataCatalog catalog; + + @Inject + public LiveCatalogResolver(final MetadataCatalog catalog) + { + this.catalog = catalog; + } + + private DatasourceFacade datasourceSpec(String name) + { + TableId tableId = TableId.datasource(name); + ResolvedTable table = catalog.resolveTable(tableId); + if (table == null) { + return null; + } + if (!DatasourceDefn.isDatasource(table)) { + return null; + } + return new DatasourceFacade(table); + } + + /** + * Create a {@link DruidTable} based on the physical segments, catalog entry, or both. + */ + @Override + public DruidTable resolveDatasource(String name, PhysicalDatasourceMetadata dsMetadata) + { + DatasourceFacade dsSpec = datasourceSpec(name); + + // No catalog metadata. If there is no physical metadata, then the + // datasource does not exist. Else, if there is physical metadata, the + // datasource is based entirely on the physical information. + if (dsSpec == null) { + return dsMetadata == null ? null : new DatasourceTable(dsMetadata); + } + if (dsMetadata == null) { + // Datasource exists only in the catalog: no physical segments. + return emptyDatasource(name, dsSpec); + } else { + // Datasource exists as both segments and a catalog entry. + return mergeDatasource(dsMetadata, dsSpec); + } + } + + private DruidTable emptyDatasource(String name, DatasourceFacade dsSpec) + { + RowSignature.Builder builder = RowSignature.builder(); + Map<String, EffectiveColumnMetadata> columns = new HashMap<>(); + boolean hasTime = false; + for (ColumnSpec col : dsSpec.columns()) { + EffectiveColumnMetadata colMetadata = columnFromCatalog(col, null); + if (colMetadata.name().equals(Columns.TIME_COLUMN)) { + hasTime = true; + } + builder.add(col.name(), colMetadata.druidType()); + columns.put(col.name(), colMetadata); + } + if (!hasTime) { + columns.put(Columns.TIME_COLUMN, new EffectiveColumnMetadata( + Columns.TIME_COLUMN, + ColumnType.LONG + )); + builder = RowSignature.builder() + .add(Columns.TIME_COLUMN, ColumnType.LONG) + .addAll(builder.build()); + } + + final PhysicalDatasourceMetadata mergedMetadata = new PhysicalDatasourceMetadata( + new TableDataSource(name), + builder.build(), + false, // Cannot join to an empty table + false // Cannot broadcast an empty table + ); + return new DatasourceTable( + mergedMetadata.getRowSignature(), + mergedMetadata, + new EffectiveMetadata(dsSpec, columns, true) + ); + } + + private EffectiveColumnMetadata columnFromCatalog(ColumnSpec col, ColumnType physicalType) + { + ColumnType type = Columns.druidType(col); + if (type != null) { + // Use the type that the user provided. + } else if (physicalType == null) { + // Corner case: the user has defined a column in the catalog, has + // not specified a type (meaning the user wants Druid to decide), but + // there is no data at this moment. Guess String as the type for the + // null values. If new segments appear between now and execution, we'll + // convert the values to string, which is always safe. + type = ColumnType.STRING; + } else { + type = physicalType; + } + return new EffectiveColumnMetadata(col.name(), type); + } + + private DruidTable mergeDatasource( + final PhysicalDatasourceMetadata dsMetadata, + final DatasourceFacade dsSpec) + { + final RowSignature physicalSchema = dsMetadata.getRowSignature(); + Set<String> physicalCols = new HashSet<>(physicalSchema.getColumnNames()); + + // Merge columns. All catalog-defined columns come first, + // in the order defined in the catalog. + final RowSignature.Builder builder = RowSignature.builder(); + Map<String, EffectiveColumnMetadata> columns = new HashMap<>(); Review Comment: `columns` is just used as column name lookup, the order-preserving component in a `DatasourceTable` is the `RowSignature` which stores the columns in a list -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
