Put back a backwards-compatible version of sampling support functions.
Commit 83e176ec18
removed the longstanding
support functions for block sampling without any consideration of the
impact this would have on third-party FDWs. The new API is not notably
more functional for FDWs than the old, so forcing them to change doesn't
seem like a good thing. We can provide the old API as a wrapper (more
or less) around the new one for a minimal amount of extra code.
This commit is contained in:
parent
f5916bb7b5
commit
4db485e75b
|
@ -3,7 +3,7 @@
|
|||
* sampling.c
|
||||
* Relation block sampling routines.
|
||||
*
|
||||
* Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
|
||||
* Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
|
||||
* Portions Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
*
|
||||
|
@ -239,3 +239,47 @@ sampler_random_fract(SamplerRandomState randstate)
|
|||
{
|
||||
return pg_erand48(randstate);
|
||||
}
|
||||
|
||||
|
||||
/*
|
||||
* Backwards-compatible API for block sampling
|
||||
*
|
||||
* This code is now deprecated, but since it's still in use by many FDWs,
|
||||
* we should keep it for awhile at least. The functionality is the same as
|
||||
* sampler_random_fract/reservoir_init_selection_state/reservoir_get_next_S,
|
||||
* except that a common random state is used across all callers.
|
||||
*/
|
||||
static ReservoirStateData oldrs;
|
||||
|
||||
double
|
||||
anl_random_fract(void)
|
||||
{
|
||||
/* initialize if first time through */
|
||||
if (oldrs.randstate[0] == 0)
|
||||
sampler_random_init_state(random(), oldrs.randstate);
|
||||
|
||||
/* and compute a random fraction */
|
||||
return sampler_random_fract(oldrs.randstate);
|
||||
}
|
||||
|
||||
double
|
||||
anl_init_selection_state(int n)
|
||||
{
|
||||
/* initialize if first time through */
|
||||
if (oldrs.randstate[0] == 0)
|
||||
sampler_random_init_state(random(), oldrs.randstate);
|
||||
|
||||
/* Initial value of W (for use when Algorithm Z is first applied) */
|
||||
return exp(-log(sampler_random_fract(oldrs.randstate)) / n);
|
||||
}
|
||||
|
||||
double
|
||||
anl_get_next_S(double t, int n, double *stateptr)
|
||||
{
|
||||
double result;
|
||||
|
||||
oldrs.W = *stateptr;
|
||||
result = reservoir_get_next_S(&oldrs, t, n);
|
||||
*stateptr = oldrs.W;
|
||||
return result;
|
||||
}
|
||||
|
|
|
@ -198,4 +198,9 @@ extern void analyze_rel(Oid relid, RangeVar *relation, int options,
|
|||
BufferAccessStrategy bstrategy);
|
||||
extern bool std_typanalyze(VacAttrStats *stats);
|
||||
|
||||
/* in utils/misc/sampling.c --- duplicate of declarations in utils/sampling.h */
|
||||
extern double anl_random_fract(void);
|
||||
extern double anl_init_selection_state(int n);
|
||||
extern double anl_get_next_S(double t, int n, double *stateptr);
|
||||
|
||||
#endif /* VACUUM_H */
|
||||
|
|
|
@ -3,7 +3,7 @@
|
|||
* sampling.h
|
||||
* definitions for sampling functions
|
||||
*
|
||||
* Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
|
||||
* Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
|
||||
* Portions Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
* src/include/utils/sampling.h
|
||||
|
@ -13,7 +13,8 @@
|
|||
#ifndef SAMPLING_H
|
||||
#define SAMPLING_H
|
||||
|
||||
#include "storage/bufmgr.h"
|
||||
#include "storage/block.h" /* for typedef BlockNumber */
|
||||
|
||||
|
||||
/* Random generator for sampling code */
|
||||
typedef unsigned short SamplerRandomState[3];
|
||||
|
@ -23,6 +24,7 @@ extern void sampler_random_init_state(long seed,
|
|||
extern double sampler_random_fract(SamplerRandomState randstate);
|
||||
|
||||
/* Block sampling methods */
|
||||
|
||||
/* Data structure for Algorithm S from Knuth 3.4.2 */
|
||||
typedef struct
|
||||
{
|
||||
|
@ -40,7 +42,8 @@ extern void BlockSampler_Init(BlockSampler bs, BlockNumber nblocks,
|
|||
extern bool BlockSampler_HasMore(BlockSampler bs);
|
||||
extern BlockNumber BlockSampler_Next(BlockSampler bs);
|
||||
|
||||
/* Reservoid sampling methods */
|
||||
/* Reservoir sampling methods */
|
||||
|
||||
typedef struct
|
||||
{
|
||||
double W;
|
||||
|
@ -52,4 +55,11 @@ typedef ReservoirStateData *ReservoirState;
|
|||
extern void reservoir_init_selection_state(ReservoirState rs, int n);
|
||||
extern double reservoir_get_next_S(ReservoirState rs, double t, int n);
|
||||
|
||||
/* Old API, still in use by assorted FDWs */
|
||||
/* For backwards compatibility, these declarations are duplicated in vacuum.h */
|
||||
|
||||
extern double anl_random_fract(void);
|
||||
extern double anl_init_selection_state(int n);
|
||||
extern double anl_get_next_S(double t, int n, double *stateptr);
|
||||
|
||||
#endif /* SAMPLING_H */
|
||||
|
|
Loading…
Reference in New Issue