FennelParameters

This page documents parameters which control the behavior of Fennel. Some of these are generic, some are component-specific, and some are test-specific. Many also appear in higher-level systems built on Fennel such as FarragoSystemParameters and LucidDbSystemParameters.

Applies To	Name	Domain	Default Value	Description
Common	resourceDir	filesystem path to directory	${FENNEL_HOME}/common	Location from which localized resource string files will be loaded.
Common	jniHandleTraceFile	filesystem path to file	empty string	If non-empty, controls location where JNI handle tracing output is written
Cache	cachePagesMax	32-bit integer (number of pages)	1024	Determines upper bound for number of pages cache can allocate. On startup, actual upper bound is set to the larger of this parameter and cachePagesInit. Subsequently, changes to cachePagesInit are limited by upper bound calculated at startup.
Cache	cachePagesInit	32-bit integer (number of pages)	1024	Sets number of page memory buffers to allocate from the OS for Fennel's data cache (also used as a pool for volatile scratch memory allocated by ExecStreams). Increasing it after startup causes new free buffers to be allocated; decreasing it causes buffers to be released (flushing them first if they contain dirty data).
Cache	cachePageSize	32-bit integer (number of bytes; must be a power of 2)	4096	Determines contiguous size of memory buffers allocated by cache. Also determines contiguous size of pages stored on disk; these are the elemental allocation units for all disk-based data structures such as indexes.
Cache	processorCacheBytes	32-bit integer (number of bytes)	-1	Controls the amount of last-level CPU cache (typically L2, sometimes L3) to be used by memory-conscious data structures for improved cache coherence. The default value of -1 requests an automatic setting; currently this is 2MB, but may be changed to hardware autodetect in the future. This parameter is not available before v0.9.2.
Cache	cacheIdleFlushInterval	32-bit integer (number of milliseconds)	100	Controls rate at which dirty data is flushed from the cache via lazy writer thread. Set to 0 to disable the lazy writer.
Cache	prefetchPagesMax	32-bit integer (number of pages)	12	Controls size of prefetch queue for access paths which use prefetch.
Cache	prefetchThrottleRate	32-bit integer (number of pages)	10	In the event that prefetch has been throttled down due to rejected requests, controls number of successful prefetches which must occur before prefetch rate is increased again.
Cache, Resource Governor	cacheReservePercentage	integer between 1 and 99 inclusive	5	The percentage of the data cache that should be set aside for global resource usage. The remainder will be available to allocate to individual statements.
Cache, Resource Governor	expectedConcurrentStatements	32-bit integer (number of statements)	4	The percentage of the data cache that should be set aside for global resource usage. The remainder will be available to allocate to individual statements.
Tests derived from CacheTestBase	victimPolicy	{ twoq, lru, random }	twoq	Sets the cache victimization algorithm.
Tests derived from CacheTestBase	diskPages	32-bit integer (number of pages)	1000	Size of file to create for tests which need persistence but which do not create a database
Cache when default twoq victim policy is being used	freshmenPageQueuePercentage	integer between 0 and 100 inclusive	25	Percentage of the total cache set aside for the freshmen queue
Cache when default twoq victim policy is being used	pageHistoryQueuePercentage	integer between 0 and 100 inclusive	100	Percentage of the total number of cache pages that dictates the number of pages in the history queue.
Device I/O	deviceSchedulerType	{ threadPool, aioLinux, aioPolling, aioSignal }	system-dependent	Controls the scheduler used for disk I/O. threadPool means to fake asynchronous I/O via a thread pool, and use buffered file access. On Linux, aioLinux means to use libaio for asynchronous I/O, with O_DIRECT for unbuffered file access. The default is to to use libaio if available, otherwise to fallback to threadPool. On Windows, ioCompletionPort (the default) means to use asynchronous I/O via completion ports and unbuffered file access. aioSignal and aioPolling are for Unix variants such as Solaris which are currently not supported by Fennel. In all cases, if an unrecognized or unsupported value is set, the system silently reverts to default behavior to avoid causing startup failures.
Device I/O	deviceSchedulerThreadCounts	32-bit integer (number of threads)	1	Suggested number of threads to dedicate to scheduling activities; the scheduler may adjust this number based on the setting for deviceSchedulerMaxRequests.
Device I/O	deviceSchedulerMaxRequests	32-bit integer (number of I/O requests)	1024	The maximum number of simultaneous requests that this scheduler should be able to handle; additional requests may be queued (or rejected for prefetch).
Database	databaseDir	filesystem path to directory	must be set explicitly, except tests will set this to working directory automatically	Location where all data, temp, and log files will be created.
Database	forceTxns	{ false, true }	false	Whether to force out all dirty pages at each commit. For logical transaction logging, this is not necessary, but some storage implementations such as LucidDB treat the database itself as a log structure.
Database (only when forceTxns=true)	disableSnapshots	{ false, true }	false	Normally, forceTxns=true implies usage of snapshot page versioning; setting disableSnapshots=true reverts to using unversioned page updates.
Database	databaseInitSize	32-bit integer (number of pages)	1000	Determines the number of pages desired when calculating the initial size of Fennel's db.dat file.
Database	databaseMaxSize	32-bit integer (number of pages)	no limit	Determines maximum size to which db.dat file can grow. Further allocations will fail even if space remains in the file system.
Database	databaseIncrementSize	32-bit integer (number of pages)	1	Determines number of pages by which to automatically extend the db.dat file when all existing pages have been allocated.
Database	tempInitSize	32-bit integer (number of pages)	1000	Determines the number of pages desired when calculating the initial size of Fennel's temp.dat file.
Database	tempMaxSize	32-bit integer (number of pages)	no limit	Determines maximum size to which temp.dat file can grow. Further allocations will fail even if space remains in the file system.
Database	tempIncrementSize	32-bit integer (number of pages)	1	Determines number of pages by which to automatically extend the temp.dat file when all existing pages have been allocated.
Database	databaseShadowLogInitSize	32-bit integer (number of pages)	1000	Determines the number of pages desired when calculating the initial size of Fennel's shadowlog.dat file.
Database	databaseShadowLogMaxSize	32-bit integer (number of pages)	no limit	Determines maximum size to which shadowlog.dat file can grow. Further allocations will fail even if space remains in the file system.
Database	databaseShadowLogIncrementSize	32-bit integer (number of pages)	1	Determines number of pages by which to automatically extend the shadowlog.dat file when all existing pages have been allocated.
Database	databaseTxnLogInitSize	32-bit integer (number of pages)	1000	Determines the number of pages desired when calculating the initial size of Fennel's txnlog.dat file.
Database	databaseTxnLogMaxSize	32-bit integer (number of pages)	no limit	Determines maximum size to which txnlog.dat file can grow. Further allocations will fail even if space remains in the file system.
Database	databaseTxnLogIncrementSize	32-bit integer (number of pages)	1	Determines number of pages by which to automatically extend the txnlog.dat file when all existing pages have been allocated.
Database	groupCommitInterval	32-bit integer (number of milliseconds)	30	Determines maximum latency for group commit.
ParallelExecStreamScheduler	degreeOfParallelism	32-bit integer (number of concurrent tasks)	4	Configures the thread pool used for parallel execution.
Tests	testSuiteNameBoost	test suite name	set automatically based on test being run	Internal parameter; should not be set explicitly.
Tests	testTraceFileName	filesystem path to file	set automatically based on test being run to ${FENNEL_HOME}/trace/%testSuiteNameBoost%_trace.log	Controls location of test trace output.
Tests	testTraceLevel	integer in the domain { 300, 400, 500, 700, 800, 900, 1000, 10000 } from the TraceLevel enum	800 (TRACE_CONFIG)	Controls verbosity of test trace output.
Tests	testStatsFileName	filesystem path to file	/tmp/fennel.stats	Controls location of stats monitoring file.
Tests	testTraceStdout	string (--Jvs 20:13, 25 November 2008 (EST): shouldn't this be boolean instead?)	empty string	If non-empty, trace output is also written to stdout.
Tests	testDictionaryFileName	filesystem path to file	dictWords	Location of dictionary words file used as data by some tests.
Tests derived from ThreadedTestBase	testDuration	32-bit integer (number of seconds)	10	Duration for executing multi-threaded test.
Tests derived from ThreadedTestBase	defaultThreads	32-bit integer (number of threads)	1	Default number of threads to execute for a given activity, if not overridden by a more specific parameter such as readSeqThreads.
Tests derived from PagingTestBase	randomOps	32-bit integer	5000	Total number of requests to be executed by each random I/O thread.
Tests derived from PagingTestBase	resizeCache	0 or 1 (--Jvs 20:13, 25 November 2008 (EST): shouldn't this be boolean?)	1	Whether to dynamically shrink and expand the cache during the test.
Tests derived from PagingTestBase	readSeqThreads, writeSeqThreads, readRandThreads, writeRandThreads, readNoWaitThreads, writeNoWaitThreads, writeSkipThreads, scratchThreads, prefetchThreads, prefetchBatchThreads, allocateThreads, deallocateThreads	32-bit integer (number of threads)	setting for %defaultThreads%	This family of parameters controls the number of threads to execute for carrying out various kinds of concurrent I/O, as indicated by the parameter names.
BTreeTxnTest	insertsPerTxn	32-bit integer (number of insert operations)	5	Controls the number of operations executed per insert transaction.
BTreeTxnTest	deletesPerTxn	32-bit integer (number of delete operations)	5	Controls the number of operations executed per delete transaction.
BTreeTxnTest	keysPerScan	32-bit integer (number of btree entries)	5	Controls the number of leaf btree entries iterated over by each scan transaction.
BTreeTxnTest	maxKey	32-bit integer (key value)	1000000	Controls the maximum number randomly generated for a key value.
BTreeTxnTest	checkpointInterval	32-bit integer (number of seconds)	20	Controls the interval in between checkpoint operations.
BTreeTxnTest	testRollback	0 or 1 (--Jvs 20:13, 25 November 2008 (EST): shouldn't this be boolean?)	1	Whether to cause half of the transactions to end in rollback (instead of just committing all of them).
BTreeTxnTest	insertThreads	32-bit integer (number of threads)	setting for %defaultThreads%	Controls the number of threads carrying out concurrent insert transactions.
BTreeTxnTest	deleteThreads	32-bit integer (number of threads)	setting for %defaultThreads%	Controls the number of threads carrying out concurrent delete transactions.
BTreeTxnTest	scanThreads	32-bit integer (number of threads)	setting for %defaultThreads%	Controls the number of threads carrying out concurrent scan transactions.
BTreeTxnTest	fuzzyChecpoint	0 or 1 (--Jvs 20:13, 25 November 2008 (EST): shouldn't this be boolean?)	1	Whether to use fuzzy checkpoints instead of sharp checkpoints.