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https://git.postgresql.org/git/postgresql.git
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(overlaying low byte of page size) and add HEAP_HASOID bit to t_infomask, per earlier discussion. Simplify scheme for overlaying fields in tuple header (no need for cmax to live in more than one place). Don't try to clear infomask status bits in tqual.c --- not safe to do it there. Don't try to force output table of a SELECT INTO to have OIDs, either. Get rid of unnecessarily complex three-state scheme for TupleDesc.tdhasoids, which has already caused one recent failure. Improve documentation.
444 lines
12 KiB
C
444 lines
12 KiB
C
#include "postgres.h"
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#include <ctype.h>
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#include "executor/spi.h"
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#include "commands/trigger.h"
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/*
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* Trigger function accepts variable number of arguments:
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*
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* 1. relation in which to store the substrings
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* 2. fields to extract substrings from
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*
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* The relation in which to insert *must* have the following layout:
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*
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* string varchar(#)
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* id oid
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*
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* where # is the largest size of the varchar columns being indexed
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*
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* Example:
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*
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* -- Create the SQL function based on the compiled shared object
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* create function fti() returns trigger as
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* '/usr/local/pgsql/lib/contrib/fti.so' language 'C';
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*
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* -- Create the FTI table
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* create table product_fti (string varchar(255), id oid);
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*
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* -- Create an index to assist string matches
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* create index product_fti_string_idx on product_fti (string);
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*
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* -- Create an index to assist trigger'd deletes
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* create index product_fti_id_idx on product_fti (id);
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*
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* -- Create an index on the product oid column to assist joins
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* -- between the fti table and the product table
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* create index product_oid_idx on product (oid);
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*
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* -- Create the trigger to perform incremental changes to the full text index.
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* create trigger product_fti_trig after update or insert or delete on product
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* for each row execute procedure fti(product_fti, title, artist);
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* ^^^^^^^^^^^
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* table where full text index is stored
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* ^^^^^^^^^^^^^
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* columns to index in the base table
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*
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* After populating 'product', try something like:
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*
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* SELECT DISTINCT(p.*) FROM product p, product_fti f1, product_fti f2 WHERE
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* f1.string ~ '^slippery' AND f2.string ~ '^wet' AND p.oid=f1.id AND p.oid=f2.id;
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*
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* To check that your indicies are being used correctly, make sure you
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* EXPLAIN SELECT ... your test query above.
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*
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* CHANGELOG
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* ---------
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*
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* august 3 2001
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* Extended fti function to accept more than one column as a
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* parameter and all specified columns are indexed. Changed
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* all uses of sprintf to snprintf. Made error messages more
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* consistent.
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*
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* march 4 1998 Changed breakup() to return less substrings. Only breakup
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* in word parts which are in turn shortened from the start
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* of the word (ie. word, ord, rd)
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* Did allocation of substring buffer outside of breakup()
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*
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* oct. 5 1997, fixed a bug in string breakup (where there are more nonalpha
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* characters between words then 1).
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*
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* oct 4-5 1997 implemented the thing, at least the basic functionallity
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* of it all....
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*
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* TODO
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* ----
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*
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* prevent generating duplicate words for an oid in the fti table
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* save a plan for deletes
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* create a function that will make the index *after* we have populated
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* the main table (probably first delete all contents to be sure there's
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* nothing in it, then re-populate the fti-table)
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*
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* can we do something with operator overloading or a seperate function
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* that can build the final query automatigally?
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*/
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#define MAX_FTI_QUERY_LENGTH 8192
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extern Datum fti(PG_FUNCTION_ARGS);
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static char *breakup(char *, char *);
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static bool is_stopword(char *);
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static bool new_tuple = false;
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#ifdef USE_STOP_WORDS
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/* THIS LIST MUST BE IN SORTED ORDER, A BINARY SEARCH IS USED!!!! */
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char *StopWords[] = { /* list of words to skip in indexing */
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"no",
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"the",
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"yes"
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};
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#endif /* USE_STOP_WORDS */
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/* stuff for caching query-plans, stolen from contrib/spi/\*.c */
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typedef struct
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{
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char *ident;
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int nplans;
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void **splan;
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} EPlan;
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static EPlan *InsertPlans = NULL;
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static EPlan *DeletePlans = NULL;
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static int nInsertPlans = 0;
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static int nDeletePlans = 0;
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static EPlan *find_plan(char *ident, EPlan ** eplan, int *nplans);
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/***********************************************************************/
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PG_FUNCTION_INFO_V1(fti);
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Datum
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fti(PG_FUNCTION_ARGS)
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{
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TriggerData *trigdata;
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Trigger *trigger; /* to get trigger name */
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int nargs; /* # of arguments */
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char **args; /* arguments */
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char *relname; /* triggered relation name */
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Relation rel; /* triggered relation */
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char *indexname; /* name of table for substrings */
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HeapTuple rettuple = NULL;
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TupleDesc tupdesc; /* tuple description */
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bool isinsert = false;
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bool isdelete = false;
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int ret;
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char query[MAX_FTI_QUERY_LENGTH];
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Oid oid;
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/*
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* FILE *debug;
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*/
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/*
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* debug = fopen("/dev/xconsole", "w"); fprintf(debug, "FTI: entered
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* function\n"); fflush(debug);
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*/
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if (!CALLED_AS_TRIGGER(fcinfo))
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elog(ERROR, "Full Text Indexing: Not fired by trigger manager");
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/* It's safe to cast now that we've checked */
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trigdata = (TriggerData *) fcinfo->context;
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if (TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
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elog(ERROR, "Full Text Indexing: Can't process STATEMENT events");
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if (TRIGGER_FIRED_BEFORE(trigdata->tg_event))
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elog(ERROR, "Full Text Indexing: Must be fired AFTER event");
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if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
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isinsert = true;
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if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
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{
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isdelete = true;
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isinsert = true;
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}
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if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
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isdelete = true;
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trigger = trigdata->tg_trigger;
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rel = trigdata->tg_relation;
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relname = SPI_getrelname(rel);
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rettuple = trigdata->tg_trigtuple;
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if (isdelete && isinsert) /* is an UPDATE */
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rettuple = trigdata->tg_newtuple;
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if ((ret = SPI_connect()) < 0)
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elog(ERROR, "Full Text Indexing: SPI_connect: Failed, returned %d\n", ret);
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nargs = trigger->tgnargs;
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if (nargs < 2)
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elog(ERROR, "Full Text Indexing: Trigger must have at least 2 arguments\n");
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args = trigger->tgargs;
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indexname = args[0];
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tupdesc = rel->rd_att; /* what the tuple looks like (?) */
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/* get oid of current tuple, needed by all, so place here */
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oid = HeapTupleGetOid(rettuple);
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if (!OidIsValid(oid))
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elog(ERROR, "Full Text Indexing: Oid of current tuple is invalid");
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if (isdelete)
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{
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void *pplan;
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Oid *argtypes;
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Datum values[1];
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EPlan *plan;
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int i;
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snprintf(query, MAX_FTI_QUERY_LENGTH, "D%s", indexname);
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for (i = 1; i < nargs; i++)
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snprintf(query, MAX_FTI_QUERY_LENGTH, "%s$%s", query, args[i]);
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plan = find_plan(query, &DeletePlans, &nDeletePlans);
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if (plan->nplans <= 0)
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{
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argtypes = (Oid *) palloc(sizeof(Oid));
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argtypes[0] = OIDOID;
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snprintf(query, MAX_FTI_QUERY_LENGTH, "DELETE FROM %s WHERE id = $1", indexname);
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pplan = SPI_prepare(query, 1, argtypes);
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if (!pplan)
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elog(ERROR, "Full Text Indexing: SPI_prepare: Returned NULL in delete");
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pplan = SPI_saveplan(pplan);
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if (pplan == NULL)
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elog(ERROR, "Full Text Indexing: SPI_saveplan: Returned NULL in delete");
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plan->splan = (void **) malloc(sizeof(void *));
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*(plan->splan) = pplan;
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plan->nplans = 1;
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}
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values[0] = oid;
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ret = SPI_execp(*(plan->splan), values, NULL, 0);
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if (ret != SPI_OK_DELETE)
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elog(ERROR, "Full Text Indexing: SPI_execp: Error executing plan in delete");
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}
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if (isinsert)
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{
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char *substring;
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char *column;
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void *pplan;
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Oid *argtypes;
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Datum values[2];
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int colnum;
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struct varlena *data;
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EPlan *plan;
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int i;
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char *buff;
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char *string;
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snprintf(query, MAX_FTI_QUERY_LENGTH, "I%s", indexname);
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for (i = 1; i < nargs; i++)
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snprintf(query, MAX_FTI_QUERY_LENGTH, "%s$%s", query, args[i]);
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plan = find_plan(query, &InsertPlans, &nInsertPlans);
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/* no plan yet, so allocate mem for argtypes */
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if (plan->nplans <= 0)
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{
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argtypes = (Oid *) palloc(2 * sizeof(Oid));
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argtypes[0] = VARCHAROID; /* create table t_name (string
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* varchar, */
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argtypes[1] = OIDOID; /* id oid); */
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/* prepare plan to gain speed */
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snprintf(query, MAX_FTI_QUERY_LENGTH, "INSERT INTO %s (string, id) VALUES ($1, $2)",
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indexname);
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pplan = SPI_prepare(query, 2, argtypes);
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if (!pplan)
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elog(ERROR, "Full Text Indexing: SPI_prepare: Returned NULL in insert");
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pplan = SPI_saveplan(pplan);
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if (pplan == NULL)
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elog(ERROR, "Full Text Indexing: SPI_saveplan: Returned NULL in insert");
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plan->splan = (void **) malloc(sizeof(void *));
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*(plan->splan) = pplan;
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plan->nplans = 1;
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}
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/* prepare plan for query */
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for (i = 0; i < nargs - 1; i++)
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{
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colnum = SPI_fnumber(tupdesc, args[i + 1]);
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if (colnum == SPI_ERROR_NOATTRIBUTE)
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elog(ERROR, "Full Text Indexing: SPI_fnumber: Column '%s' of '%s' not found", args[i + 1], indexname);
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/* Get the char* representation of the column */
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column = SPI_getvalue(rettuple, tupdesc, colnum);
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/* make sure we don't try to index NULL's */
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if (column)
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{
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string = column;
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while (*string != '\0')
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{
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*string = tolower((unsigned char) *string);
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string++;
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}
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data = (struct varlena *) palloc(sizeof(int32) + strlen(column) +1);
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buff = palloc(strlen(column) + 1);
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/* saves lots of calls in while-loop and in breakup() */
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new_tuple = true;
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while ((substring = breakup(column, buff)))
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{
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int l;
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l = strlen(substring);
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data->vl_len = l + sizeof(int32);
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memcpy(VARDATA(data), substring, l);
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values[0] = PointerGetDatum(data);
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values[1] = oid;
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ret = SPI_execp(*(plan->splan), values, NULL, 0);
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if (ret != SPI_OK_INSERT)
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elog(ERROR, "Full Text Indexing: SPI_execp: Error executing plan in insert");
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}
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pfree(buff);
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pfree(data);
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}
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}
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}
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SPI_finish();
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return PointerGetDatum(rettuple);
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}
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static char *
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breakup(char *string, char *substring)
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{
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static char *last_start;
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static char *cur_pos;
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if (new_tuple)
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{
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cur_pos = last_start = &string[strlen(string) - 1];
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new_tuple = false; /* don't initialize this next time */
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}
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while (cur_pos > string) /* don't read before start of 'string' */
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{
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/*
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* skip pieces at the end of a string that are not alfa-numeric
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* (ie. 'string$%^&', last_start first points to '&', and after
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* this to 'g'
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*/
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if (!isalnum((unsigned char) *last_start))
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{
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while (!isalnum((unsigned char) *last_start) &&
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last_start > string)
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last_start--;
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cur_pos = last_start;
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}
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cur_pos--; /* substrings are at minimum 2 characters
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* long */
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if (isalnum((unsigned char) *cur_pos))
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{
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/* Houston, we have a substring! :) */
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memcpy(substring, cur_pos, last_start - cur_pos + 1);
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substring[last_start - cur_pos + 1] = '\0';
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if (!is_stopword(substring))
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return substring;
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}
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else
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{
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last_start = cur_pos - 1;
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cur_pos = last_start;
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}
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}
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return NULL; /* we've processed all of 'string' */
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}
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/* copied from src/backend/parser/keywords.c and adjusted for our situation*/
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static bool
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is_stopword(char *text)
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{
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#ifdef USE_STOP_WORDS
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char **StopLow; /* for list of stop-words */
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char **StopHigh;
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char **StopMiddle;
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int difference;
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StopLow = &StopWords[0]; /* initialize stuff for binary search */
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StopHigh = endof(StopWords);
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/* Loop invariant: *StopLow <= text < *StopHigh */
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while (StopLow < StopHigh)
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{
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StopMiddle = StopLow + (StopHigh - StopLow) / 2;
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difference = strcmp(*StopMiddle, text);
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if (difference == 0)
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return (true);
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else if (difference < 0)
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StopLow = StopMiddle + 1;
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else
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StopHigh = StopMiddle;
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}
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#endif /* USE_STOP_WORDS */
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return (false);
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}
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/* for caching of query plans, stolen from contrib/spi/\*.c */
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static EPlan *
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find_plan(char *ident, EPlan ** eplan, int *nplans)
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{
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EPlan *newp;
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int i;
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if (*nplans > 0)
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{
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for (i = 0; i < *nplans; i++)
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{
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if (strcmp((*eplan)[i].ident, ident) == 0)
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break;
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}
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if (i != *nplans)
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return (*eplan + i);
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*eplan = (EPlan *) realloc(*eplan, (i + 1) * sizeof(EPlan));
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newp = *eplan + i;
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}
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else
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{
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newp = *eplan = (EPlan *) malloc(sizeof(EPlan));
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(*nplans) = i = 0;
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}
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newp->ident = (char *) malloc(strlen(ident) + 1);
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strcpy(newp->ident, ident);
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newp->nplans = 0;
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newp->splan = NULL;
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(*nplans)++;
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return (newp);
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}
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