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| <table width="100%" summary="page for read.jdbc {SparkR}"><tr><td>read.jdbc {SparkR}</td><td style="text-align: right;">R Documentation</td></tr></table> |
| |
| <h2>Create a SparkDataFrame representing the database table accessible via JDBC URL</h2> |
| |
| <h3>Description</h3> |
| |
| <p>Additional JDBC database connection properties can be set (...) |
| </p> |
| |
| |
| <h3>Usage</h3> |
| |
| <pre> |
| read.jdbc(url, tableName, partitionColumn = NULL, lowerBound = NULL, |
| upperBound = NULL, numPartitions = 0L, predicates = list(), ...) |
| </pre> |
| |
| |
| <h3>Arguments</h3> |
| |
| <table summary="R argblock"> |
| <tr valign="top"><td><code>url</code></td> |
| <td> |
| <p>JDBC database url of the form <code>jdbc:subprotocol:subname</code></p> |
| </td></tr> |
| <tr valign="top"><td><code>tableName</code></td> |
| <td> |
| <p>the name of the table in the external database</p> |
| </td></tr> |
| <tr valign="top"><td><code>partitionColumn</code></td> |
| <td> |
| <p>the name of a column of integral type that will be used for partitioning</p> |
| </td></tr> |
| <tr valign="top"><td><code>lowerBound</code></td> |
| <td> |
| <p>the minimum value of <code>partitionColumn</code> used to decide partition stride</p> |
| </td></tr> |
| <tr valign="top"><td><code>upperBound</code></td> |
| <td> |
| <p>the maximum value of <code>partitionColumn</code> used to decide partition stride</p> |
| </td></tr> |
| <tr valign="top"><td><code>numPartitions</code></td> |
| <td> |
| <p>the number of partitions, This, along with <code>lowerBound</code> (inclusive), |
| <code>upperBound</code> (exclusive), form partition strides for generated WHERE |
| clause expressions used to split the column <code>partitionColumn</code> evenly. |
| This defaults to SparkContext.defaultParallelism when unset.</p> |
| </td></tr> |
| <tr valign="top"><td><code>predicates</code></td> |
| <td> |
| <p>a list of conditions in the where clause; each one defines one partition</p> |
| </td></tr> |
| <tr valign="top"><td><code>...</code></td> |
| <td> |
| <p>additional JDBC database connection named properties.</p> |
| </td></tr> |
| </table> |
| |
| |
| <h3>Details</h3> |
| |
| <p>Only one of partitionColumn or predicates should be set. Partitions of the table will be |
| retrieved in parallel based on the <code>numPartitions</code> or by the predicates. |
| </p> |
| <p>Don't create too many partitions in parallel on a large cluster; otherwise Spark might crash |
| your external database systems. |
| </p> |
| |
| |
| <h3>Value</h3> |
| |
| <p>SparkDataFrame |
| </p> |
| |
| |
| <h3>Note</h3> |
| |
| <p>read.jdbc since 2.0.0 |
| </p> |
| |
| |
| <h3>Examples</h3> |
| |
| <pre><code class="r">## Not run: |
| ##D sparkR.session() |
| ##D jdbcUrl <- "jdbc:mysql://localhost:3306/databasename" |
| ##D df <- read.jdbc(jdbcUrl, "table", predicates = list("field<=123"), user = "username") |
| ##D df2 <- read.jdbc(jdbcUrl, "table2", partitionColumn = "index", lowerBound = 0, |
| ##D upperBound = 10000, user = "username", password = "password") |
| ## End(Not run) |
| </code></pre> |
| |
| |
| <hr /><div style="text-align: center;">[Package <em>SparkR</em> version 2.3.1 <a href="00Index.html">Index</a>]</div> |
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