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ba8f828b88
changes from the vendor branch as well, backing the db-1.82 changes. This file should now be the same as it was in rev 1.1.1.2. |
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.. | ||
extern.h | ||
hash_bigkey.c | ||
hash_buf.c | ||
hash_func.c | ||
hash_log2.c | ||
hash_page.c | ||
hash.c | ||
hash.h | ||
hsearch.c | ||
Makefile.inc | ||
ndbm.c | ||
page.h | ||
README | ||
search.h |
# @(#)README 8.1 (Berkeley) 6/4/93 This package implements a superset of the hsearch and dbm/ndbm libraries. Test Programs: All test programs which need key/data pairs expect them entered with key and data on separate lines tcreat3.c Takes bucketsize (bsize), fill factor (ffactor), and initial number of elements (nelem). Creates a hash table named hashtest containing the keys/data pairs entered from standard in. thash4.c Takes bucketsize (bsize), fill factor (ffactor), initial number of elements (nelem) bytes of cache (ncached), and file from which to read data (fname) Creates a table from the key/data pairs on standard in and then does a read of each key/data in fname tdel.c Takes bucketsize (bsize), and fill factor (ffactor). file from which to read data (fname) Reads each key/data pair from fname and deletes the key from the hash table hashtest tseq.c Reads the key/data pairs in the file hashtest and writes them to standard out. tread2.c Takes butes of cache (ncached). Reads key/data pairs from standard in and looks them up in the file hashtest. tverify.c Reads key/data pairs from standard in, looks them up in the file hashtest, and verifies that the data is correct. NOTES: The file search.h is provided for using the hsearch compatible interface on BSD systems. On System V derived systems, search.h should appear in /usr/include. The man page ../man/db.3 explains the interface to the hashing system. The file hash.ps is a postscript copy of a paper explaining the history, implementation, and performance of the hash package. "bugs" or idiosyncracies If you have a lot of overflows, it is possible to run out of overflow pages. Currently, this will cause a message to be printed on stderr. Eventually, this will be indicated by a return error code. If you are using the ndbm interface and exit without flushing or closing the file, you may lose updates since the package buffers all writes. Also, the db interface only creates a single database file. To avoid overwriting the user's original file, the suffix ".db" is appended to the file name passed to dbm_open. Additionally, if your code "knows" about the historic .dir and .pag files, it will break. There is a fundamental difference between this package and the old hsearch. Hsearch requires the user to maintain the keys and data in the application's allocated memory while hash takes care of all storage management. The down side is that the byte strings passed in the ENTRY structure must be null terminated (both the keys and the data).