http://git-wip-us.apache.org/repos/asf/incubator-impala/blob/75c46918/docs/build/html/topics/impala_num_nodes.html ---------------------------------------------------------------------- diff --git a/docs/build/html/topics/impala_num_nodes.html b/docs/build/html/topics/impala_num_nodes.html new file mode 100644 index 0000000..9f98c68 --- /dev/null +++ b/docs/build/html/topics/impala_num_nodes.html @@ -0,0 +1,61 @@ +<!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_query_options.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="num_nodes"><link rel="stylesheet" type="text/css" href="../commonltr.css"><title>NUM_NODES Query Option</title></head><body id="num_nodes"><main role="main"><article role="article" aria-labelledby="ariaid-title1"> + + <h1 class="title topictitle1" id="ariaid-title1">NUM_NODES Query Option</h1> + + + + <div class="body conbody"> + + <p class="p"> + + Limit the number of nodes that process a query, typically during debugging. + </p> + + <p class="p"> + <strong class="ph b">Type:</strong> numeric + </p> + +<p class="p"> + <strong class="ph b">Allowed values:</strong> Only accepts the values 0 + (meaning all nodes) or 1 (meaning all work is done on the coordinator node). +</p> + + <p class="p"> + <strong class="ph b">Default:</strong> 0 + </p> + + <p class="p"> + <strong class="ph b">Usage notes:</strong> + </p> + + <p class="p"> + If you are diagnosing a problem that you suspect is due to a timing issue due to + distributed query processing, you can set <code class="ph codeph">NUM_NODES=1</code> to verify + if the problem still occurs when all the work is done on a single node. + </p> + + <p class="p"> + You might set the <code class="ph codeph">NUM_NODES</code> option to 1 briefly, during <code class="ph codeph">INSERT</code> or + <code class="ph codeph">CREATE TABLE AS SELECT</code> statements. Normally, those statements produce one or more data + files per data node. If the write operation involves small amounts of data, a Parquet table, and/or a + partitioned table, the default behavior could produce many small files when intuitively you might expect + only a single output file. <code class="ph codeph">SET NUM_NODES=1</code> turns off the <span class="q">"distributed"</span> aspect of the + write operation, making it more likely to produce only one or a few data files. + </p> + + <div class="note warning note_warning"><span class="note__title warningtitle">Warning:</span> + <p class="p"> + Because this option results in increased resource utilization on a single host, + it could cause problems due to contention with other Impala statements or + high resource usage. Symptoms could include queries running slowly, exceeding the memory limit, + or appearing to hang. Use it only in a single-user development/test environment; + <strong class="ph b">do not</strong> use it in a production environment or in a cluster with a high-concurrency + or high-volume or performance-critical workload. + </p> + </div> + + + </div> +<nav role="navigation" class="related-links"><div class="familylinks"><div class="parentlink"><strong>Parent topic:</strong> <a class="link" href="../topics/impala_query_options.html">Query Options for the SET Statement</a></div></div></nav></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_num_scanner_threads.html ---------------------------------------------------------------------- diff --git a/docs/build/html/topics/impala_num_scanner_threads.html b/docs/build/html/topics/impala_num_scanner_threads.html new file mode 100644 index 0000000..9bd9375 --- /dev/null +++ b/docs/build/html/topics/impala_num_scanner_threads.html @@ -0,0 +1,27 @@ +<!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_query_options.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="num_scanner_threads"><link rel="stylesheet" type="text/css" href="../commonltr.css"><title>NUM_SCANNER_THREADS Query Option</title></head><body id="num_scanner_threads"><main role="main"><article role="article" aria-labelledby="ariaid-title1"> + + <h1 class="title topictitle1" id="ariaid-title1">NUM_SCANNER_THREADS Query Option</h1> + + + + <div class="body conbody"> + + <p class="p"> + + Maximum number of scanner threads (on each node) used for each query. By default, Impala uses as many cores + as are available (one thread per core). You might lower this value if queries are using excessive resources + on a busy cluster. Impala imposes a maximum value automatically, so a high value has no practical effect. + </p> + + <p class="p"> + <strong class="ph b">Type:</strong> numeric + </p> + + <p class="p"> + <strong class="ph b">Default:</strong> 0 + </p> + + </div> +<nav role="navigation" class="related-links"><div class="familylinks"><div class="parentlink"><strong>Parent topic:</strong> <a class="link" href="../topics/impala_query_options.html">Query Options for the SET Statement</a></div></div></nav></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_odbc.html ---------------------------------------------------------------------- diff --git a/docs/build/html/topics/impala_odbc.html b/docs/build/html/topics/impala_odbc.html new file mode 100644 index 0000000..cd9aec9 --- /dev/null +++ b/docs/build/html/topics/impala_odbc.html @@ -0,0 +1,24 @@ +<!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_config.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="impala_odbc"><link rel="stylesheet" type="text/css" href="../commonltr.css"><title>Configuring Impala to Work with ODBC</title></head><body id="impala_odbc"><main role="main"><article role="article" aria-labelledby="impala_odbc__odbc"> + + <h1 class="title topictitle1" id="impala_odbc__odbc">Configuring Impala to Work with ODBC</h1> + + + <div class="body conbody"> + + <p class="p"> + + Third-party products, especially business intelligence and reporting tools, can access Impala + using the ODBC protocol. For the best experience, ensure any third-party product you intend to use is supported. + Verifying support includes checking that the versions of Impala, ODBC, the operating system, the + Apache Hadoop distribution, and the third-party product have all been approved by the appropriate suppliers + for use together. To configure your systems to use ODBC, download and install a connector, typically from + the supplier of the third-party product or the Hadoop distribution. + You may need to sign in and accept license agreements before accessing the pages required for downloading + ODBC connectors. + </p> + + </div> + +<nav role="navigation" class="related-links"><div class="familylinks"><div class="parentlink"><strong>Parent topic:</strong> <a class="link" href="../topics/impala_config.html">Managing Impala</a></div></div></nav></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_offset.html ---------------------------------------------------------------------- diff --git a/docs/build/html/topics/impala_offset.html b/docs/build/html/topics/impala_offset.html new file mode 100644 index 0000000..6de1515 --- /dev/null +++ b/docs/build/html/topics/impala_offset.html @@ -0,0 +1,67 @@ +<!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_select.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="offset"><link rel="stylesheet" type="text/css" href="../commonltr.css"><title>OFFSET Clause</title></head><body id="offset"><main role="main"><article role="article" aria-labelledby="ariaid-title1"> + + <h1 class="title topictitle1" id="ariaid-title1">OFFSET Clause</h1> + + + <div class="body conbody"> + + <p class="p"> + The <code class="ph codeph">OFFSET</code> clause in a <code class="ph codeph">SELECT</code> query causes the result set to start some + number of rows after the logical first item. The result set is numbered starting from zero, so <code class="ph codeph">OFFSET + 0</code> produces the same result as leaving out the <code class="ph codeph">OFFSET</code> clause. Always use this clause + in combination with <code class="ph codeph">ORDER BY</code> (so that it is clear which item should be first, second, and so + on) and <code class="ph codeph">LIMIT</code> (so that the result set covers a bounded range, such as items 0-9, 100-199, + and so on). + </p> + + <p class="p"> + In Impala 1.2.1 and higher, you can combine a <code class="ph codeph">LIMIT</code> clause with an <code class="ph codeph">OFFSET</code> + clause to produce a small result set that is different from a top-N query, for example, to return items 11 + through 20. This technique can be used to simulate <span class="q">"paged"</span> results. Because Impala queries typically + involve substantial amounts of I/O, use this technique only for compatibility in cases where you cannot + rewrite the application logic. For best performance and scalability, wherever practical, query as many + items as you expect to need, cache them on the application side, and display small groups of results to + users using application logic. + </p> + + <p class="p"> + <strong class="ph b">Examples:</strong> + </p> + + <p class="p"> + The following example shows how you could run a <span class="q">"paging"</span> query originally written for a traditional + database application. Because typical Impala queries process megabytes or gigabytes of data and read large + data files from disk each time, it is inefficient to run a separate query to retrieve each small group of + items. Use this technique only for compatibility while porting older applications, then rewrite the + application code to use a single query with a large result set, and display pages of results from the cached + result set. + </p> + +<pre class="pre codeblock"><code>[localhost:21000] > create table numbers (x int); +[localhost:21000] > insert into numbers select x from very_long_sequence; +Inserted 1000000 rows in 1.34s +[localhost:21000] > select x from numbers order by x limit 5 offset 0; ++----+ +| x | ++----+ +| 1 | +| 2 | +| 3 | +| 4 | +| 5 | ++----+ +[localhost:21000] > select x from numbers order by x limit 5 offset 5; ++----+ +| x | ++----+ +| 6 | +| 7 | +| 8 | +| 9 | +| 10 | ++----+ +</code></pre> + </div> +<nav role="navigation" class="related-links"><div class="familylinks"><div class="parentlink"><strong>Parent topic:</strong> <a class="link" href="../topics/impala_select.html">SELECT Statement</a></div></div></nav></article></main></body></html> \ No newline at end of file
