http://git-wip-us.apache.org/repos/asf/incubator-impala/blob/75c46918/docs/build/html/topics/impala_troubleshooting.html ---------------------------------------------------------------------- diff --git a/docs/build/html/topics/impala_troubleshooting.html b/docs/build/html/topics/impala_troubleshooting.html new file mode 100644 index 0000000..7728ee4 --- /dev/null +++ b/docs/build/html/topics/impala_troubleshooting.html @@ -0,0 +1,370 @@ +<!DOCTYPE html + SYSTEM "about:legacy-compat"> +<html lang="en"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><meta charset="UTF-8"><meta name="copyright" content="(C) Copyright 2017"><meta name="DC.rights.owner" content="(C) Copyright 2017"><meta name="DC.Type" content="concept"><meta name="DC.Relation" scheme="URI" content="../topics/impala_webui.html"><meta name="DC.Relation" scheme="URI" content="../topics/impala_breakpad.html"><meta name="prodname" content="Impala"><meta name="prodname" content="Impala"><meta name="version" content="Impala 2.8.x"><meta name="version" content="Impala 2.8.x"><meta name="DC.Format" content="XHTML"><meta name="DC.Identifier" content="troubleshooting"><link rel="stylesheet" type="text/css" href="../commonltr.css"><title>Troubleshooting Impala</title></head><body id="troubleshooting"><main role="main"><article role="article" aria-labelledby="ariaid-title1"> + + <h1 class="title topictitle1" id="ariaid-title1">Troubleshooting Impala</h1> + + + <div class="body conbody"> + + <p class="p"> + + Troubleshooting for Impala requires being able to diagnose and debug problems + with performance, network connectivity, out-of-memory conditions, disk space usage, + and crash or hang conditions in any of the Impala-related daemons. + </p> + + <p class="p toc inpage"> + The following sections describe the general troubleshooting procedures to diagnose + different kinds of problems: + </p> + + </div> + + <nav role="navigation" class="related-links"><ul class="ullinks"><li class="link ulchildlink"><strong><a href="../topics/impala_webui.html">Impala Web User Interface for Debugging</a></strong><br></li><li class="link ulchildlink"><strong><a href="../topics/impala_breakpad.html">Breakpad Minidumps for Impala (Impala 2.6 or higher only)</a></strong><br></li></ul></nav><article class="topic concept nested1" aria-labelledby="ariaid-title2" id="troubleshooting__trouble_sql"> + + <h2 class="title topictitle2" id="ariaid-title2">Troubleshooting Impala SQL Syntax Issues</h2> + + <div class="body conbody"> + + <p class="p"> + In general, if queries issued against Impala fail, you can try running these same queries against Hive. + </p> + + <ul class="ul"> + <li class="li"> + If a query fails against both Impala and Hive, it is likely that there is a problem with your query or + other elements of your <span class="keyword"></span> environment: + <ul class="ul"> + <li class="li"> + Review the <a class="xref" href="impala_langref.html#langref">Language Reference</a> to ensure your query is + valid. + </li> + + <li class="li"> + Check <a class="xref" href="impala_reserved_words.html#reserved_words">Impala Reserved Words</a> to see if any database, table, + column, or other object names in your query conflict with Impala reserved words. + Quote those names with backticks (<code class="ph codeph">``</code>) if so. + </li> + + <li class="li"> + Check <a class="xref" href="impala_functions.html#builtins">Impala Built-In Functions</a> to confirm whether Impala supports all the + built-in functions being used by your query, and whether argument and return types are the + same as you expect. + </li> + + <li class="li"> + Review the <a class="xref" href="impala_logging.html#logs_debug">contents of the Impala logs</a> for any information that may be useful in identifying the + source of the problem. + </li> + </ul> + </li> + + <li class="li"> + If a query fails against Impala but not Hive, it is likely that there is a problem with your Impala + installation. + </li> + </ul> + </div> + </article> + + <article class="topic concept nested1" aria-labelledby="ariaid-title3" id="troubleshooting__trouble_io"> + <h2 class="title topictitle2" id="ariaid-title3">Troubleshooting I/O Capacity Problems</h2> + <div class="body conbody"> + <p class="p"> + Impala queries are typically I/O-intensive. If there is an I/O problem with storage devices, + or with HDFS itself, Impala queries could show slow response times with no obvious cause + on the Impala side. Slow I/O on even a single DataNode could result in an overall slowdown, because + queries involving clauses such as <code class="ph codeph">ORDER BY</code>, <code class="ph codeph">GROUP BY</code>, or <code class="ph codeph">JOIN</code> + do not start returning results until all DataNodes have finished their work. + </p> + <p class="p"> + To test whether the Linux I/O system itself is performing as expected, run Linux commands like + the following on each DataNode: + </p> +<pre class="pre codeblock"><code> +$ sudo sysctl -w vm.drop_caches=3 vm.drop_caches=0 +vm.drop_caches = 3 +vm.drop_caches = 0 +$ sudo dd if=/dev/sda bs=1M of=/dev/null count=1k +1024+0 records in +1024+0 records out +1073741824 bytes (1.1 GB) copied, 5.60373 s, 192 MB/s +$ sudo dd if=/dev/sdb bs=1M of=/dev/null count=1k +1024+0 records in +1024+0 records out +1073741824 bytes (1.1 GB) copied, 5.51145 s, 195 MB/s +$ sudo dd if=/dev/sdc bs=1M of=/dev/null count=1k +1024+0 records in +1024+0 records out +1073741824 bytes (1.1 GB) copied, 5.58096 s, 192 MB/s +$ sudo dd if=/dev/sdd bs=1M of=/dev/null count=1k +1024+0 records in +1024+0 records out +1073741824 bytes (1.1 GB) copied, 5.43924 s, 197 MB/s +</code></pre> + <p class="p"> + On modern hardware, a throughput rate of less than 100 MB/s typically indicates + a performance issue with the storage device. Correct the hardware problem before + continuing with Impala tuning or benchmarking. + </p> + </div> + </article> + + + <article class="topic concept nested1" aria-labelledby="ariaid-title4" id="troubleshooting__trouble_cookbook"> + + <h2 class="title topictitle2" id="ariaid-title4">Impala Troubleshooting Quick Reference</h2> + + <div class="body conbody"> + + <p class="p"> + The following table lists common problems and potential solutions. + </p> + + <table class="table"><caption></caption><colgroup><col style="width:14.285714285714285%"><col style="width:42.857142857142854%"><col style="width:42.857142857142854%"></colgroup><thead class="thead"> + <tr class="row"> + <th class="entry nocellnorowborder" id="trouble_cookbook__entry__1"> + Symptom + </th> + <th class="entry nocellnorowborder" id="trouble_cookbook__entry__2"> + Explanation + </th> + <th class="entry nocellnorowborder" id="trouble_cookbook__entry__3"> + Recommendation + </th> + </tr> + </thead><tbody class="tbody"> + <tr class="row"> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__1 "> + Impala takes a long time to start. + </td> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__2 "> + Impala instances with large numbers of tables, partitions, or data files take longer to start + because the metadata for these objects is broadcast to all <span class="keyword cmdname">impalad</span> nodes and + cached. + </td> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__3 "> + Adjust timeout and synchronicity settings. + </td> + </tr> + <tr class="row"> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__1 "> + <p class="p"> + Joins fail to complete. + </p> + </td> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__2 "> + <p class="p"> + There may be insufficient memory. During a join, data from the second, third, and so on sets to + be joined is loaded into memory. If Impala chooses an inefficient join order or join mechanism, + the query could exceed the total memory available. + </p> + </td> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__3 "> + <p class="p"> + Start by gathering statistics with the <code class="ph codeph">COMPUTE STATS</code> statement for each table + involved in the join. Consider specifying the <code class="ph codeph">[SHUFFLE]</code> hint so that data from + the joined tables is split up between nodes rather than broadcast to each node. If tuning at the + SQL level is not sufficient, add more memory to your system or join smaller data sets. + </p> + </td> + </tr> + <tr class="row"> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__1 "> + <p class="p"> + Queries return incorrect results. + </p> + </td> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__2 "> + <p class="p"> + Impala metadata may be outdated after changes are performed in Hive. + </p> + </td> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__3 "> + <p class="p"> + Where possible, use the appropriate Impala statement (<code class="ph codeph">INSERT</code>, <code class="ph codeph">LOAD + DATA</code>, <code class="ph codeph">CREATE TABLE</code>, <code class="ph codeph">ALTER TABLE</code>, <code class="ph codeph">COMPUTE + STATS</code>, and so on) rather than switching back and forth between Impala and Hive. Impala + automatically broadcasts the results of DDL and DML operations to all Impala nodes in the + cluster, but does not automatically recognize when such changes are made through Hive. After + inserting data, adding a partition, or other operation in Hive, refresh the metadata for the + table as described in <a class="xref" href="impala_refresh.html#refresh">REFRESH Statement</a>. + </p> + </td> + </tr> + <tr class="row"> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__1 "> + <p class="p"> + Queries are slow to return results. + </p> + </td> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__2 "> + <p class="p"> + Some <code class="ph codeph">impalad</code> instances may not have started. Using a browser, connect to the + host running the Impala state store. Connect using an address of the form + <code class="ph codeph">http://<var class="keyword varname">hostname</var>:<var class="keyword varname">port</var>/metrics</code>. + </p> + + <div class="p"> + <div class="note note note_note"><span class="note__title notetitle">Note:</span> + Replace <var class="keyword varname">hostname</var> and <var class="keyword varname">port</var> with the hostname and port of + your Impala state store host machine and web server port. The default port is 25010. + </div> + The number of <code class="ph codeph">impalad</code> instances listed should match the expected number of + <code class="ph codeph">impalad</code> instances installed in the cluster. There should also be one + <code class="ph codeph">impalad</code> instance installed on each DataNode + </div> + </td> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__3 "> + <p class="p"> + Ensure Impala is installed on all DataNodes. Start any <code class="ph codeph">impalad</code> instances that + are not running. + </p> + </td> + </tr> + <tr class="row"> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__1 "> + <p class="p"> + Queries are slow to return results. + </p> + </td> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__2 "> + <p class="p"> + Impala may not be configured to use native checksumming. Native checksumming uses + machine-specific instructions to compute checksums over HDFS data very quickly. Review Impala + logs. If you find instances of "<code class="ph codeph">INFO util.NativeCodeLoader: Loaded the + native-hadoop</code>" messages, native checksumming is not enabled. + </p> + </td> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__3 "> + <p class="p"> + Ensure Impala is configured to use native checksumming as described in + <a class="xref" href="impala_config_performance.html#config_performance">Post-Installation Configuration for Impala</a>. + </p> + </td> + </tr> + <tr class="row"> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__1 "> + <p class="p"> + Queries are slow to return results. + </p> + </td> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__2 "> + <p class="p"> + Impala may not be configured to use data locality tracking. + </p> + </td> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__3 "> + <p class="p"> + Test Impala for data locality tracking and make configuration changes as necessary. Information + on this process can be found in <a class="xref" href="impala_config_performance.html#config_performance">Post-Installation Configuration for Impala</a>. + </p> + </td> + </tr> + <tr class="row"> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__1 "> + <p class="p"> + Attempts to complete Impala tasks such as executing INSERT-SELECT actions fail. The Impala logs + include notes that files could not be opened due to permission denied. + </p> + </td> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__2 "> + <p class="p"> + This can be the result of permissions issues. For example, you could use the Hive shell as the + hive user to create a table. After creating this table, you could attempt to complete some + action, such as an INSERT-SELECT on the table. Because the table was created using one user and + the INSERT-SELECT is attempted by another, this action may fail due to permissions issues. + </p> + </td> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__3 "> + <p class="p"> + In general, ensure the Impala user has sufficient permissions. In the preceding example, ensure + the Impala user has sufficient permissions to the table that the Hive user created. + </p> + </td> + </tr> + <tr class="row"> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__1 "> + <p class="p"> + Impala fails to start up, with the <span class="keyword cmdname">impalad</span> logs referring to errors connecting + to the statestore service and attempts to re-register. + </p> + </td> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__2 "> + <p class="p"> + A large number of databases, tables, partitions, and so on can require metadata synchronization, + particularly on startup, that takes longer than the default timeout for the statestore service. + </p> + </td> + <td class="entry nocellnorowborder" headers="trouble_cookbook__entry__3 "> + <p class="p"> + Configure the statestore timeout value and possibly other settings related to the frequency of + statestore updates and metadata loading. See + <a class="xref" href="impala_timeouts.html#statestore_timeout">Increasing the Statestore Timeout</a> and + <a class="xref" href="impala_scalability.html#statestore_scalability">Scalability Considerations for the Impala Statestore</a>. + </p> + </td> + </tr> + </tbody></table> + + + </div> + </article> + + + + + + <article class="topic concept nested1" aria-labelledby="ariaid-title5" id="troubleshooting__webui_snippet"> + <h2 class="title topictitle2" id="ariaid-title5">Impala Web User Interface for Debugging</h2> + <div class="body conbody"> + <div class="p"> + + + Each of the Impala daemons (<span class="keyword cmdname">impalad</span>, <span class="keyword cmdname">statestored</span>, + and <span class="keyword cmdname">catalogd</span>) includes a built-in web server that displays + diagnostic and status information: + <ul class="ul"> + <li class="li"> + <p class="p"> + The <span class="keyword cmdname">impalad</span> web UI (default port: 25000) includes + information about configuration settings, running and completed queries, and associated performance and + resource usage for queries. In particular, the <span class="ph uicontrol">Details</span> link for each query displays + alternative views of the query including a graphical representation of the plan, and the + output of the <code class="ph codeph">EXPLAIN</code>, <code class="ph codeph">SUMMARY</code>, and <code class="ph codeph">PROFILE</code> + statements from <span class="keyword cmdname">impala-shell</span>. + Each host that runs the <span class="keyword cmdname">impalad</span> daemon has + its own instance of the web UI, with details about those queries for which that + host served as the coordinator. The <span class="keyword cmdname">impalad</span> web UI is mainly + for diagnosing query problems that can be traced to a particular node. + </p> + </li> + <li class="li"> + <p class="p"> + The <span class="keyword cmdname">statestored</span> web UI (default port: 25010) includes + information about memory usage, configuration settings, and ongoing health checks + performed by this daemon. Because there is only a single instance of this + daemon within any cluster, you view the web UI only on the particular host + that serves as the Impala Statestore. + </p> + </li> + <li class="li"> + <p class="p"> + The <span class="keyword cmdname">catalogd</span> web UI (default port: 25020) includes + information about the databases, tables, and other objects managed by Impala, + in addition to the resource usage and configuration settings of the daemon itself. + The catalog information is represented as the underlying Thrift data structures. + Because there is only a single instance of this daemon within any cluster, you view the + web UI only on the particular host that serves as the Impala Catalog Server. + </p> + </li> + </ul> + </div> + <p class="p"> + For full details, see <a class="xref" href="impala_webui.html#webui">Impala Web User Interface for Debugging</a>. + </p> + </div> + </article> + +</article></main></body></html> \ No newline at end of file
http://git-wip-us.apache.org/repos/asf/incubator-impala/blob/75c46918/docs/build/html/topics/impala_truncate_table.html ---------------------------------------------------------------------- diff --git a/docs/build/html/topics/impala_truncate_table.html b/docs/build/html/topics/impala_truncate_table.html new file mode 100644 index 0000000..9e5b530 --- /dev/null +++ b/docs/build/html/topics/impala_truncate_table.html @@ -0,0 +1,200 @@ +<!DOCTYPE html + SYSTEM "about:legacy-compat"> +<html lang="en"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><meta charset="UTF-8"><meta name="copyright" content="(C) Copyright 2017"><meta name="DC.rights.owner" content="(C) Copyright 2017"><meta name="DC.Type" content="concept"><meta name="DC.Relation" scheme="URI" content="../topics/impala_langref_sql.html"><meta name="prodname" content="Impala"><meta name="prodname" content="Impala"><meta name="version" content="Impala 2.8.x"><meta name="version" content="Impala 2.8.x"><meta name="DC.Format" content="XHTML"><meta name="DC.Identifier" content="truncate_table"><link rel="stylesheet" type="text/css" href="../commonltr.css"><title>TRUNCATE TABLE Statement (Impala 2.3 or higher only)</title></head><body id="truncate_table"><main role="main"><article role="article" aria-labelledby="ariaid-title1"> + + <h1 class="title topictitle1" id="ariaid-title1">TRUNCATE TABLE Statement (<span class="keyword">Impala 2.3</span> or higher only)</h1> + + + + <div class="body conbody"> + + <p class="p"> + + Removes the data from an Impala table while leaving the table itself. + </p> + + <p class="p"> + <strong class="ph b">Syntax:</strong> + </p> + +<pre class="pre codeblock"><code>TRUNCATE TABLE <span class="ph">[IF EXISTS]</span> [<var class="keyword varname">db_name</var>.]<var class="keyword varname">table_name</var></code></pre> + + <p class="p"> + <strong class="ph b">Statement type:</strong> DDL + </p> + + <p class="p"> + <strong class="ph b">Usage notes:</strong> + </p> + + <p class="p"> + Often used to empty tables that are used during ETL cycles, after the data has been copied to another + table for the next stage of processing. This statement is a low-overhead alternative to dropping and + recreating the table, or using <code class="ph codeph">INSERT OVERWRITE</code> to replace the data during the + next ETL cycle. + </p> + + <p class="p"> + This statement removes all the data and associated data files in the table. It can remove data files from internal tables, + external tables, partitioned tables, and tables mapped to HBase or the Amazon Simple Storage Service (S3). + The data removal applies to the entire table, including all partitions of a partitioned table. + </p> + + <p class="p"> + Any statistics produced by the <code class="ph codeph">COMPUTE STATS</code> statement are reset when the data is removed. + </p> + + <p class="p"> + Make sure that you are in the correct database before truncating a table, either by issuing a + <code class="ph codeph">USE</code> statement first or by using a fully qualified name + <code class="ph codeph"><var class="keyword varname">db_name</var>.<var class="keyword varname">table_name</var></code>. + </p> + + <p class="p"> + The optional <code class="ph codeph">IF EXISTS</code> clause makes the statement succeed whether or not the table exists. + If the table does exist, it is truncated; if it does not exist, the statement has no effect. This capability is + useful in standardized setup scripts that are might be run both before and after some of the tables exist. + This clause is available in <span class="keyword">Impala 2.5</span> and higher. + </p> + + <p class="p"> + Any HDFS data files removed by this statement go into the HDFS trashcan, from which you can recover them + within a defined time interval if this operation turns out to be a mistake. + </p> + + <p class="p"> + For other tips about managing and reclaiming Impala disk space, see + <a class="xref" href="../shared/../topics/impala_disk_space.html#disk_space">Managing Disk Space for Impala Data</a>. + </p> + + <p class="p"> + <strong class="ph b">Amazon S3 considerations:</strong> + </p> + <p class="p"> + Although Impala cannot write new data to a table stored in the Amazon + S3 filesystem, the <code class="ph codeph">TRUNCATE TABLE</code> statement can remove data files from S3. + See <a class="xref" href="impala_s3.html#s3">Using Impala with the Amazon S3 Filesystem</a> for details about working with S3 tables. + </p> + + <p class="p"> + <strong class="ph b">Cancellation:</strong> Cannot be cancelled. + </p> + + <p class="p"> + <strong class="ph b">HDFS permissions:</strong> + </p> + <p class="p"> + The user ID that the <span class="keyword cmdname">impalad</span> daemon runs under, + typically the <code class="ph codeph">impala</code> user, must have write + permission for all the files and directories that make up the table. + </p> + + <p class="p"> + <strong class="ph b">Kudu considerations:</strong> + </p> + <p class="p"> + Currently, the <code class="ph codeph">TRUNCATE TABLE</code> statement cannot be used with Kudu tables. + </p> + + <p class="p"> + <strong class="ph b">Examples:</strong> + </p> + + <p class="p"> + The following example shows a table containing some data and with table and column statistics. + After the <code class="ph codeph">TRUNCATE TABLE</code> statement, the data is removed and the statistics + are reset. + </p> + +<pre class="pre codeblock"><code>CREATE TABLE truncate_demo (x INT); +INSERT INTO truncate_demo VALUES (1), (2), (4), (8); +SELECT COUNT(*) FROM truncate_demo; ++----------+ +| count(*) | ++----------+ +| 4 | ++----------+ +COMPUTE STATS truncate_demo; ++-----------------------------------------+ +| summary | ++-----------------------------------------+ +| Updated 1 partition(s) and 1 column(s). | ++-----------------------------------------+ +SHOW TABLE STATS truncate_demo; ++-------+--------+------+--------------+-------------------+--------+-------------------+ +| #Rows | #Files | Size | Bytes Cached | Cache Replication | Format | Incremental stats | ++-------+--------+------+--------------+-------------------+--------+-------------------+ +| 4 | 1 | 8B | NOT CACHED | NOT CACHED | TEXT | false | ++-------+--------+------+--------------+-------------------+--------+-------------------+ +SHOW COLUMN STATS truncate_demo; ++--------+------+------------------+--------+----------+----------+ +| Column | Type | #Distinct Values | #Nulls | Max Size | Avg Size | ++--------+------+------------------+--------+----------+----------+ +| x | INT | 4 | -1 | 4 | 4 | ++--------+------+------------------+--------+----------+----------+ + +-- After this statement, the data and the table/column stats will be gone. +TRUNCATE TABLE truncate_demo; + +SELECT COUNT(*) FROM truncate_demo; ++----------+ +| count(*) | ++----------+ +| 0 | ++----------+ +SHOW TABLE STATS truncate_demo; ++-------+--------+------+--------------+-------------------+--------+-------------------+ +| #Rows | #Files | Size | Bytes Cached | Cache Replication | Format | Incremental stats | ++-------+--------+------+--------------+-------------------+--------+-------------------+ +| -1 | 0 | 0B | NOT CACHED | NOT CACHED | TEXT | false | ++-------+--------+------+--------------+-------------------+--------+-------------------+ +SHOW COLUMN STATS truncate_demo; ++--------+------+------------------+--------+----------+----------+ +| Column | Type | #Distinct Values | #Nulls | Max Size | Avg Size | ++--------+------+------------------+--------+----------+----------+ +| x | INT | -1 | -1 | 4 | 4 | ++--------+------+------------------+--------+----------+----------+ +</code></pre> + + <p class="p"> + The following example shows how the <code class="ph codeph">IF EXISTS</code> clause allows the <code class="ph codeph">TRUNCATE TABLE</code> + statement to be run without error whether or not the table exists: + </p> + +<pre class="pre codeblock"><code>CREATE TABLE staging_table1 (x INT, s STRING); +Fetched 0 row(s) in 0.33s + +SHOW TABLES LIKE 'staging*'; ++----------------+ +| name | ++----------------+ +| staging_table1 | ++----------------+ +Fetched 1 row(s) in 0.25s + +-- Our ETL process involves removing all data from several staging tables +-- even though some might be already dropped, or not created yet. + +TRUNCATE TABLE IF EXISTS staging_table1; +Fetched 0 row(s) in 5.04s + +TRUNCATE TABLE IF EXISTS staging_table2; +Fetched 0 row(s) in 0.25s + +TRUNCATE TABLE IF EXISTS staging_table3; +Fetched 0 row(s) in 0.25s +</code></pre> + + <p class="p"> + <strong class="ph b">Related information:</strong> + </p> + + <p class="p"> + <a class="xref" href="impala_tables.html#tables">Overview of Impala Tables</a>, + <a class="xref" href="impala_alter_table.html#alter_table">ALTER TABLE Statement</a>, <a class="xref" href="impala_create_table.html#create_table">CREATE TABLE Statement</a>, + <a class="xref" href="impala_partitioning.html#partitioning">Partitioning for Impala Tables</a>, <a class="xref" href="impala_tables.html#internal_tables">Internal Tables</a>, + <a class="xref" href="impala_tables.html#external_tables">External Tables</a> + </p> + + </div> +<nav role="navigation" class="related-links"><div class="familylinks"><div class="parentlink"><strong>Parent topic:</strong> <a class="link" href="../topics/impala_langref_sql.html">Impala SQL Statements</a></div></div></nav></article></main></body></html> \ No newline at end of file
