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102 lines
5.4 KiB
HTML
<!--$Id: memp_stat.so,v 10.28 2000/05/25 13:47:08 dda Exp $-->
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<!--Copyright 1997, 1998, 1999, 2000 by Sleepycat Software, Inc.-->
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<html>
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<title>Berkeley DB: DbEnv.memp_stat</title>
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<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
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<meta name="keywords" content="embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,java,C,C++">
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<a name="2"><!--meow--></a>
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<table><tr valign=top>
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<td>
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<h1>DbEnv.memp_stat</h1>
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</td>
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<td width="1%">
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<a href="../api_java/java_index.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a>
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</td></tr></table>
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<tt>
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<h3><pre>
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import com.sleepycat.db.*;
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<p>
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public DbMpoolStat memp_stat()
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throws DbException;
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<p>
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public DbMpoolFStat[] memp_fstat()
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throws DbException;
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</pre></h3>
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<h1>Description</h1>
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<p>The DbEnv.memp_stat and <a href="../api_java/memp_stat.html">DbEnv.memp_fstat</a> method create statistical
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structures and return to the caller. The statistics include the number
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of files participating in the pool, the active pages in the pool, and
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information as to how effective the cache has been.
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<p>The DbEnv.memp_stat method creates a DbMpoolStat object containing global
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statistics. The following data fields are available:
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<p><dl compact>
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<dt>public long st_gbytes;<dd>Gigabytes of cache (total cache size is st_gbytes + st_bytes)
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<dt>public long st_bytes;<dd>Bytes of cache (total cache size is st_gbytes + st_bytes)
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<dt>public int st_ncache;<dd>Number of caches.
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<dt>public int st_regsize;<dd>Individual cache size.
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<dt>public int st_cache_hit;<dd>Requested pages found in the cache.
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<dt>public int st_cache_miss;<dd>Requested pages not found in the cache.
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<dt>public int st_map;<dd>Requested pages mapped into the process' address space (there is no
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available information as to whether or not this request caused disk I/O,
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although examining the application page fault rate may be helpful).
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<dt>public int st_page_create;<dd>Pages created in the cache.
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<dt>public int st_page_in;<dd>Pages read into the cache.
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<dt>public int st_page_out;<dd>Pages written from the cache to the backing file.
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<dt>public int st_ro_evict;<dd>Clean pages forced from the cache.
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<dt>public int st_rw_evict;<dd>Dirty pages forced from the cache.
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<dt>public int st_hash_buckets;<dd>Number of hash buckets in buffer hash table.
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<dt>public int st_hash_searches;<dd>Total number of buffer hash table lookups.
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<dt>public int st_hash_longest;<dd>The longest chain ever encountered in buffer hash table lookups.
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<dt>public int st_hash_examined;<dd>Total number of hash elements traversed during hash table lookups.
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<dt>public int st_page_clean;<dd>Clean pages currently in the cache.
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<dt>public int st_page_dirty;<dd>Dirty pages currently in the cache.
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<dt>public int st_page_trickle;<dd>Dirty pages written using the <a href="../api_java/memp_trickle.html">DbEnv.memp_trickle</a> interface.
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<dt>public int st_region_wait;<dd>The number of times that a thread of control was forced to wait before
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obtaining the region lock.
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<dt>public int st_region_nowait;<dd>The number of times that a thread of control was able to obtain
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the region lock without waiting.
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</dl>
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<p>The <a href="../api_java/memp_stat.html">DbEnv.memp_fstat</a> method creates an array of DbMpoolFStat objects
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containing statistics for individual files in the pool. Each
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DbMpoolFStat object contains statistics for an individual DbMpoolFile.
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The following data fields are available for each DbMpoolFStat object:
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<p><dl compact>
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<dt>public String file_name;<dd>The name of the file.
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<dt>public long st_pagesize;<dd>Page size in bytes.
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<dt>public int st_cache_hit;<dd>Requested pages found in the cache.
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<dt>public int st_cache_miss;<dd>Requested pages not found in the cache.
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<dt>public int st_map;<dd>Requested pages mapped into the process' address space.
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<dt>public int st_page_create;<dd>Pages created in the cache.
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<dt>public int st_page_in;<dd>Pages read into the cache.
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<dt>public int st_page_out;<dd>Pages written from the cache to the backing file.
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</dl>
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<p>The DbEnv.memp_stat method throws an exception that encapsulates a non-zero error value on
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failure.
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<h1>Errors</h1>
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<p>The DbEnv.memp_stat method may fail and throw an exception encapsulating a non-zero error for the following conditions:
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<p><dl compact>
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<p><dt>EINVAL<dd>An invalid flag value or parameter was specified.
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</dl>
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<p>The DbEnv.memp_stat method may fail and throw an exception for errors specified for other Berkeley DB and C library or system methods.
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If a catastrophic error has occurred, the DbEnv.memp_stat method may fail and throw
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a <a href="../api_java/runrec_class.html">DbRunRecoveryException</a>, in which case all subsequent Berkeley DB calls
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will fail in the same way.
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<h3>Class</h3>
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<a href="../api_java/dbenv_class.html">DbEnv</a>
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<h1>See Also</h1>
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<a href="../api_java/memp_stat.html">DbEnv.memp_fstat</a>,
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<a href="../api_java/memp_stat.html">DbEnv.memp_stat</a>
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and
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<a href="../api_java/memp_trickle.html">DbEnv.memp_trickle</a>.
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</tt>
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