NIFI-3093 HIVE Support for QueryDatabaseTable #1281

patricker · 2016-11-29T22:03:34Z

This update adds HIVE support to QueryDatabaseTable.

I included a few changes to GenerateTableFetch, but these were only for compatability with the new properties added to the DB Adapter interface. This does NOT add support to GenerateTableFetch for HIVE (as I don't think paging HIVE is possible).

I'm expecting this will need a few tweaks, just let me know.

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mattyb149 · 2016-11-30T16:41:07Z

...tandard-processors/src/main/java/org/apache/nifi/processors/standard/GenerateTableFetch.java

@@ -186,8 +186,10 @@ public void onTrigger(final ProcessContext context, final ProcessSessionFactory
            try (final Connection con = dbcpService.getConnection();
                 final Statement st = con.createStatement()) {

-                final Integer queryTimeout = context.getProperty(QUERY_TIMEOUT).asTimePeriod(TimeUnit.SECONDS).intValue();
-                st.setQueryTimeout(queryTimeout); // timeout in seconds
+                if(dbAdapter.getSupportsStatementTimeout()) {


This makes sense to me, but when we were talking about supporting Hive in ExecuteSQL, there were concerns about those drivers that don't support statement timeouts, which is one reason why there's a separate Hive NAR (and Select/PutHiveQL processors). This was before DatabaseAdapter came along, so perhaps now this can be alleviated as you've done here. Does this work when using a HiveConnectionPool? Or are you using a DBCPConnectionPool that points to Hive JARs? It seems like if this works with a HiveConnectionPool (with your changes to JdbcCommon below), then the Select/PutHiveQL processors could be deprecated.

I used a HiveConnectionPool. Still easiest way to handle Kerberos, custom Hive-Site.xml, etc...

mattyb149 · 2016-11-30T16:44:02Z

...i-standard-processors/src/main/java/org/apache/nifi/processors/standard/util/JdbcCommon.java

@@ -284,7 +291,7 @@ public static Schema createSchema(final ResultSet rs, String recordName, boolean
                    break;

                case INTEGER:
-                    if (meta.isSigned(i)) {
+                    if (!dbAdapter.getSupportsMetaDataColumnIsSigned() || meta.isSigned(i)) {


If the DB doesn't support isSigned(), should we treat them all as Longs? I assume it's done this way if Hive returns INTEGER as the type and Integer objects for values. I wonder if there's another DB that doesn't support isSigned() and could return Long objects. In that case we might want another check for getSupportsMetaDataColumnIsSigned() (and for the type of object) when storing the values into the record.

Your spot on. Originally I had this without the !, but in my table I had an INT and when I tried to put it into an Avro Long field it threw an exception.

mattyb149 · 2016-11-30T16:44:23Z

...i-standard-processors/src/main/java/org/apache/nifi/processors/standard/util/JdbcCommon.java

@@ -300,7 +307,7 @@ public static Schema createSchema(final ResultSet rs, String recordName, boolean
                    // Check the precision of the BIGINT. Some databases allow arbitrary precision (> 19), but Avro won't handle that.
                    // If the precision > 19 (or is negative), use a string for the type, otherwise use a long. The object(s) will be converted
                    // to strings as necessary
-                    int precision = meta.getPrecision(i);
+                    int precision = dbAdapter.getSupportsMetaDataColumnGetPrecision()?meta.getPrecision(i):0;


Should we assume a default of zero here or < 0?

Probably -1 would be a safer choice if we can't retrieve precision. HIVE appears to supports up to DECIMAL(38,18), but who knows what might happen with other databases down the road; we don't want to accidentally lose data or start throwing exceptions for overflows.

Looks like we don't need this. I got tired of fighting exceptions one after another and started reading the HIVE JDBC driver code to find unsupported methods. It looks like I misread the code and getPrecision is a supported HIVE JDBC method call.

https://github.com/apache/hive/blob/ff67cdda1c538dc65087878eeba3e165cf3230f4/jdbc/src/java/org/apache/hive/jdbc/HiveResultSetMetaData.java

patricker · 2016-11-30T17:04:46Z

...rocessors/src/main/java/org/apache/nifi/processors/standard/db/impl/HiveDatabaseAdapter.java

+            query.append(limit);
+        }
+        if (offset != null && offset > 0) {
+            query.append(" OFFSET ");


@mattyb149 I copy/pasted this from the Generic adapter, but from what I can find HIVE has no support for OFFSET. Do you think this should throw an exception at this stage?

patricker · 2016-11-30T17:06:35Z

...essors/src/main/java/org/apache/nifi/processors/standard/AbstractDatabaseFetchProcessor.java

@@ -161,7 +161,7 @@
                .description("The type/flavor of database, used for generating database-specific code. In many cases the Generic type "
                        + "should suffice, but some databases (such as Oracle) require custom SQL clauses. ")
                .allowableValues(dbAdapters.keySet())
-                .defaultValue(dbAdapters.values().stream().findFirst().get().getName())
+                .defaultValue("Generic")


@mattyb149 In case your curious, I found that Generic may or may not be selected as the default after you start adding new DBAdapters. I ran into this exact issue when I added a new Hive DBAdapter, so I just hard coded it rather then having the default value possibly change.

mattyb149 · 2017-01-09T18:16:32Z

Do you mind rebasing this against the latest master? Please and thanks!

patricker · 2017-02-15T16:49:24Z

@mattyb149 I am still planning to update this PR. Any chance you could take a look at #1510 first and see if we can get it pulled in? It is simpler and has some direct conflicts/overlap with this PR, I'd rather get it into master before I rebase and cleanup my Hive work.

mattyb149 · 2017-03-10T17:09:09Z

#1510 is now merged, do you mind rebasing this one? Please and thanks!

patricker · 2017-04-04T08:26:39Z

@mattyb149 I'm working through this. I found a couple of issues that I'm figuring out.
Also, I might have a way to do GenerateTableFetch with HIVE, using logic similar to what you do for SQL 2008 using ROW NUMBER.

patricker · 2017-05-03T06:37:19Z

@mattyb149 I've completed the changes. I added support for GenerateTableFetch, though Hive being hive it's not all that fast...

There is one quirk, and I feel it should be documented but I'm not sure where. When using QueryDatabaseTable with Hive you need to qualify your max value column with the table name. This is because Hive always qualifies the column names in the ResultSet. Also, as a result of this, you'll need to Normalize the column names.

With GenerateTableFetch, since it pulls back the max value through a query and aliases the column name, I don't think the above issue is a problem.

ExecuteSQL should work without any special changes, just remember to select a Database Adapter when testing HIVE, this didn't used to be an available option.

ijokarumawak · 2017-06-13T06:25:02Z

@patricker This PR has now conflicts since #1798 (NIFI-2624: Avro logical types) and others are merged. Would you mind rebasing this? I'd like to review once the merge conflicts get addressed, and test to see if logical types can be used with Hive tables.
Thank you for your contribution, time and effort!

patricker · 2017-06-20T06:47:28Z

@ijokarumawak I'll work on it.

mattyb149 · 2017-09-05T20:16:57Z

@patricker Are you working on this one? If not, perhaps @ijokarumawak or I can take over.

patricker · 2017-09-11T03:12:47Z

@mattyb149 @ijokarumawak Thanks for checking in on me. I had planned to work on this, but due to recent shifts at work I don't even use HIVE anymore... If someone wants to put a bow on this I'd appreciate it.

mattyb149 reviewed Nov 30, 2016

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patricker commented Nov 30, 2016

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NIFI-3093

0c53f8b

patricker force-pushed the NIFI-3093 branch from ec5ae5e to 0c53f8b Compare May 3, 2017 06:31

MikeThomsen mentioned this pull request Mar 3, 2018

Nifi 3093 #2507

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NIFI-3093 HIVE Support for QueryDatabaseTable #1281

NIFI-3093 HIVE Support for QueryDatabaseTable #1281

patricker commented Nov 29, 2016

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NIFI-3093 HIVE Support for QueryDatabaseTable #1281

NIFI-3093 HIVE Support for QueryDatabaseTable #1281

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patricker commented Nov 29, 2016

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