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Hive QA commented on HIVE-14792: -------------------------------- | (x) *{color:red}-1 overall{color}* | \\ \\ || Vote || Subsystem || Runtime || Comment || || || || || {color:brown} Prechecks {color} || | {color:blue}0{color} | {color:blue} findbugs {color} | {color:blue} 0m 0s{color} | {color:blue} Findbugs executables are not available. {color} | | {color:green}+1{color} | {color:green} @author {color} | {color:green} 0m 0s{color} | {color:green} The patch does not contain any @author tags. {color} | || || || || {color:brown} master Compile Tests {color} || | {color:blue}0{color} | {color:blue} mvndep {color} | {color:blue} 1m 27s{color} | {color:blue} Maven dependency ordering for branch {color} | | {color:green}+1{color} | {color:green} mvninstall {color} | {color:green} 5m 43s{color} | {color:green} master passed {color} | | {color:green}+1{color} | {color:green} compile {color} | {color:green} 1m 15s{color} | {color:green} master passed {color} | | {color:green}+1{color} | {color:green} checkstyle {color} | {color:green} 0m 50s{color} | {color:green} master passed {color} | | {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 1m 4s{color} | {color:green} master passed {color} | || || || || {color:brown} Patch Compile Tests {color} || | {color:blue}0{color} | {color:blue} mvndep {color} | {color:blue} 0m 20s{color} | {color:blue} Maven dependency ordering for patch {color} | | {color:green}+1{color} | {color:green} mvninstall {color} | {color:green} 1m 33s{color} | {color:green} the patch passed {color} | | {color:green}+1{color} | {color:green} compile {color} | {color:green} 1m 18s{color} | {color:green} the patch passed {color} | | {color:green}+1{color} | {color:green} javac {color} | {color:green} 1m 18s{color} | {color:green} the patch passed {color} | | {color:red}-1{color} | {color:red} checkstyle {color} | {color:red} 0m 16s{color} | {color:red} common: The patch generated 1 new + 930 unchanged - 1 fixed = 931 total (was 931) {color} | | {color:red}-1{color} | {color:red} checkstyle {color} | {color:red} 0m 29s{color} | {color:red} ql: The patch generated 1 new + 10 unchanged - 0 fixed = 11 total (was 10) {color} | | {color:green}+1{color} | {color:green} whitespace {color} | {color:green} 0m 0s{color} | {color:green} The patch has no whitespace issues. {color} | | {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 1m 10s{color} | {color:green} the patch passed {color} | || || || || {color:brown} Other Tests {color} || | {color:green}+1{color} | {color:green} asflicense {color} | {color:green} 0m 11s{color} | {color:green} The patch does not generate ASF License warnings. {color} | | {color:black}{color} | {color:black} {color} | {color:black} 16m 1s{color} | {color:black} {color} | \\ \\ || Subsystem || Report/Notes || | Optional Tests | asflicense javac javadoc findbugs checkstyle compile | | uname | Linux hiveptest-server-upstream 3.16.0-4-amd64 #1 SMP Debian 3.16.36-1+deb8u1 (2016-09-03) x86_64 GNU/Linux | | Build tool | maven | | Personality | /data/hiveptest/working/yetus/dev-support/hive-personality.sh | | git revision | master / 9efed65 | | Default Java | 1.8.0_111 | | checkstyle | http://104.198.109.242/logs//PreCommit-HIVE-Build-8310/yetus/diff-checkstyle-common.txt | | checkstyle | http://104.198.109.242/logs//PreCommit-HIVE-Build-8310/yetus/diff-checkstyle-ql.txt | | modules | C: common ql U: . | | Console output | http://104.198.109.242/logs//PreCommit-HIVE-Build-8310/yetus.txt | | Powered by | Apache Yetus http://yetus.apache.org | This message was automatically generated. > AvroSerde reads the remote schema-file at least once per mapper, per table > reference. > ------------------------------------------------------------------------------------- > > Key: HIVE-14792 > URL: https://issues.apache.org/jira/browse/HIVE-14792 > Project: Hive > Issue Type: Bug > Affects Versions: 1.2.1, 2.1.0 > Reporter: Mithun Radhakrishnan > Assignee: Mithun Radhakrishnan > Labels: TODOC2.2, TODOC2.4 > Fix For: 3.0.0, 2.4.0, 2.2.1 > > Attachments: HIVE-14792.1.patch, HIVE-14792.3.patch > > > Avro tables that use "external" schema files stored on HDFS can cause > excessive calls to {{FileSystem::open()}}, especially for queries that spawn > large numbers of mappers. > This is because of the following code in {{AvroSerDe::initialize()}}: > {code:title=AvroSerDe.java|borderStyle=solid} > public void initialize(Configuration configuration, Properties properties) > throws SerDeException { > // ... > if (hasExternalSchema(properties) > || columnNameProperty == null || columnNameProperty.isEmpty() > || columnTypeProperty == null || columnTypeProperty.isEmpty()) { > schema = determineSchemaOrReturnErrorSchema(configuration, properties); > } else { > // Get column names and sort order > columnNames = Arrays.asList(columnNameProperty.split(",")); > columnTypes = > TypeInfoUtils.getTypeInfosFromTypeString(columnTypeProperty); > schema = getSchemaFromCols(properties, columnNames, columnTypes, > columnCommentProperty); > > properties.setProperty(AvroSerdeUtils.AvroTableProperties.SCHEMA_LITERAL.getPropName(), > schema.toString()); > } > // ... > } > {code} > For tables using {{avro.schema.url}}, every time the SerDe is initialized > (i.e. at least once per mapper), the schema file is read remotely. For > queries with thousands of mappers, this leads to a stampede to the handful > (3?) datanodes that host the schema-file. In the best case, this causes > slowdowns. > It would be preferable to distribute the Avro-schema to all mappers as part > of the job-conf. The alternatives aren't exactly appealing: > # One can't rely solely on the {{column.list.types}} stored in the Hive > metastore. (HIVE-14789). > # {{avro.schema.literal}} might not always be usable, because of the > size-limit on table-parameters. The typical size of the Avro-schema file is > between 0.5-3MB, in my limited experience. Bumping the max table-parameter > size isn't a great solution. > If the {{avro.schema.file}} were read during query-planning, and made > available as part of table-properties (but not serialized into the > metastore), the downstream logic will remain largely intact. I have a patch > that does this. -- This message was sent by Atlassian JIRA (v6.4.14#64029)