DBZ-8053 Handle empty shards #202
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,201 @@ | ||
| /* | ||
| * Copyright Debezium Authors. | ||
| * | ||
| * Licensed under the Apache Software License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0 | ||
| */ | ||
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| package io.debezium.connector.vitess; | ||
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| import static java.lang.Math.toIntExact; | ||
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| import java.util.ArrayList; | ||
| import java.util.HashSet; | ||
| import java.util.List; | ||
| import java.util.Random; | ||
| import java.util.Set; | ||
| import java.util.stream.Collectors; | ||
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| import org.slf4j.Logger; | ||
| import org.slf4j.LoggerFactory; | ||
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| import com.google.protobuf.ByteString; | ||
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| import io.debezium.annotation.VisibleForTesting; | ||
| import io.debezium.connector.vitess.connection.VitessReplicationConnection; | ||
| import io.vitess.proto.Query; | ||
| import io.vitess.proto.Vtgate; | ||
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| /** | ||
| * Class for getting metadata on Vitess, e.g., tables, shards. Supports shard-specific queries. | ||
| */ | ||
| public class VitessMetadata { | ||
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| private static final Logger LOGGER = LoggerFactory.getLogger(VitessMetadata.class); | ||
| private VitessConnectorConfig config; | ||
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| public VitessMetadata(VitessConnectorConfig config) { | ||
| this.config = config; | ||
| } | ||
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| public List<String> getShards() { | ||
| List<String> shards; | ||
| if (config.excludeEmptyShards()) { | ||
| LOGGER.info("Excluding empty shards"); | ||
| shards = getVitessShardsFromTablets(); | ||
| } | ||
| else { | ||
| shards = getVitessShards(); | ||
| } | ||
| LOGGER.info("Shards: {}", shards); | ||
| return shards; | ||
| } | ||
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| public List<String> getTables() { | ||
| Vtgate.ExecuteResponse response; | ||
| String query; | ||
| if (config.excludeEmptyShards()) { | ||
| query = "SHOW TABLES"; | ||
| List<String> shardsToQuery; | ||
| if (config.getShard() != null && !config.getShard().isEmpty()) { | ||
| LOGGER.info("Getting tables from one of the configured shards"); | ||
| shardsToQuery = config.getShard(); | ||
| } | ||
| else { | ||
| LOGGER.info("Getting tables from a non-empty shard"); | ||
| shardsToQuery = getVitessShardsFromTablets(); | ||
| } | ||
| String randomShard = shardsToQuery.get(new Random().nextInt(shardsToQuery.size())); | ||
| LOGGER.info("Get tables from shard: {}", randomShard); | ||
| response = executeQuery(query, randomShard); | ||
| } | ||
| else { | ||
| query = String.format("SHOW TABLES FROM %s", config.getKeyspace()); | ||
| response = executeQuery(query); | ||
| } | ||
| logResponse(response, query); | ||
| List<String> tables = getFlattenedRowsFromResponse(response); | ||
| LOGGER.info("All tables from keyspace {} are: {}", config.getKeyspace(), tables); | ||
| return tables; | ||
| } | ||
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| private static void logResponse(Vtgate.ExecuteResponse response, String query) { | ||
| LOGGER.debug("Got response: {} for query: {}", response, query); | ||
| } | ||
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| private List<String> getVitessShards() { | ||
| String query = String.format("SHOW VITESS_SHARDS LIKE '%s/%%'", config.getKeyspace()); | ||
| Vtgate.ExecuteResponse response = executeQuery(query); | ||
| logResponse(response, query); | ||
| List<String> rows = getFlattenedRowsFromResponse(response); | ||
| List<String> shards = rows.stream().map(fieldValue -> { | ||
| String[] parts = fieldValue.split("/"); | ||
| assert parts != null && parts.length == 2 : String.format("Wrong field format: %s", fieldValue); | ||
| return parts[1]; | ||
| }).collect(Collectors.toList()); | ||
| return shards; | ||
| } | ||
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| private List<String> getVitessShardsFromTablets() { | ||
| String query = "SHOW VITESS_TABLETS"; | ||
| Vtgate.ExecuteResponse response = executeQuery(query); | ||
| // Do not log the response since there is no way to filter tablets: it includes all tablets of all shards of all keyspaces | ||
| List<List<String>> rowValues = getRowsFromResponse(response); | ||
| List<String> shards = VitessMetadata.getNonEmptyShards(rowValues, config.getKeyspace()); | ||
| return shards; | ||
| } | ||
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| private Vtgate.ExecuteResponse executeQuery(String query) { | ||
| return executeQuery(query, null); | ||
| } | ||
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| @VisibleForTesting | ||
| protected Vtgate.ExecuteResponse executeQuery(String query, String shard) { | ||
| // Some tests need to be issue a shard-specific query, so make this visible | ||
| try (VitessReplicationConnection connection = new VitessReplicationConnection(config, null)) { | ||
| Vtgate.ExecuteResponse response; | ||
| if (shard != null) { | ||
| response = connection.execute(query, shard); | ||
| } | ||
| else { | ||
| response = connection.execute(query); | ||
| } | ||
| return response; | ||
| } | ||
| catch (Exception e) { | ||
| throw new RuntimeException(String.format("Unexpected error while running query: %s", query), e); | ||
| } | ||
| } | ||
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| private static List<String> getFlattenedRowsFromResponse(Vtgate.ExecuteResponse response) { | ||
|
There was a problem hiding this comment. Is it possible to make the rest of the methods non-static too? There was a problem hiding this comment. It is possible, but I don't think we want to, since they don't rely on any instance variables. Static clearly conveys these methods do not rely on object state. |
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| validateResponse(response); | ||
| Query.QueryResult result = response.getResult(); | ||
| validateResult(result); | ||
| List<List<String>> rows = parseRows(result.getRowsList()); | ||
| return flattenAndConcat(rows); | ||
| } | ||
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| private static List<List<String>> getRowsFromResponse(Vtgate.ExecuteResponse response) { | ||
| validateResponse(response); | ||
| Query.QueryResult result = response.getResult(); | ||
| validateResult(result); | ||
| return parseRows(result.getRowsList()); | ||
| } | ||
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| private static void validateResponse(Vtgate.ExecuteResponse response) { | ||
| assert response != null && !response.hasError() && response.hasResult() | ||
| : String.format("Error response: %s", response); | ||
| } | ||
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| private static void validateResult(Query.QueryResult result) { | ||
| List<Query.Row> rows = result.getRowsList(); | ||
| assert !rows.isEmpty() : String.format("Empty response: %s", result); | ||
| } | ||
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| @VisibleForTesting | ||
| protected static List<List<String>> parseRows(List<Query.Row> rows) { | ||
| List<List<String>> allRowValues = new ArrayList<>(); | ||
| for (Query.Row row : rows) { | ||
| List<String> currentRowValues = new ArrayList(); | ||
| List<Integer> lengths = row.getLengthsList().stream().map(x -> toIntExact(x)).collect(Collectors.toList()); | ||
| ByteString values = row.getValues(); | ||
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| int offset = 0; | ||
| for (int length : lengths) { | ||
| if (length == -1) { | ||
| currentRowValues.add(null); // Handle NULL values | ||
| } | ||
| else { | ||
| String value = values.substring(offset, offset + length).toStringUtf8(); | ||
| currentRowValues.add(value); | ||
| offset += length; | ||
| } | ||
| } | ||
| allRowValues.add(currentRowValues); | ||
| } | ||
| return allRowValues; | ||
| } | ||
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| @VisibleForTesting | ||
| protected static List<String> getNonEmptyShards(List<List<String>> vitessTabletRows, String keyspace) { | ||
| Set<String> shardSet = new HashSet<>(); | ||
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| for (List<String> row : vitessTabletRows) { | ||
| if (row.size() < 3) { | ||
| continue; // skip rows with insufficient data | ||
| } | ||
| String rowKeyspace = row.get(1); | ||
| if (rowKeyspace.equals(keyspace)) { | ||
| shardSet.add(row.get(2)); // add the shard value | ||
| } | ||
| } | ||
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| return shardSet.stream().sorted().collect(Collectors.toList()); | ||
| } | ||
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| @VisibleForTesting | ||
| protected static List<String> flattenAndConcat(List<List<String>> nestedList) { | ||
| return nestedList.stream() | ||
| .map(innerList -> String.join("", innerList)) | ||
| .collect(Collectors.toList()); | ||
| } | ||
| } | ||
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Would it be possible to convert this class to be no-static? A lot of methods uses
VitessConnectorConfigso maybe an instance can be created that will receive the config in constructor.