PostgreSQL Source Code  git master
pg_prewarm.c File Reference
#include "postgres.h"
#include <sys/stat.h>
#include <unistd.h>
#include "access/relation.h"
#include "fmgr.h"
#include "miscadmin.h"
#include "storage/bufmgr.h"
#include "storage/smgr.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
Include dependency graph for pg_prewarm.c:

Go to the source code of this file.

Enumerations

enum  PrewarmType { PREWARM_PREFETCH, PREWARM_READ, PREWARM_BUFFER }
 

Functions

 PG_FUNCTION_INFO_V1 (pg_prewarm)
 
Datum pg_prewarm (PG_FUNCTION_ARGS)
 

Variables

 PG_MODULE_MAGIC
 
static PGAlignedBlock blockbuffer
 

Enumeration Type Documentation

◆ PrewarmType

Enumerator
PREWARM_PREFETCH 
PREWARM_READ 
PREWARM_BUFFER 

Definition at line 32 of file pg_prewarm.c.

Function Documentation

◆ PG_FUNCTION_INFO_V1()

PG_FUNCTION_INFO_V1 ( pg_prewarm  )

◆ pg_prewarm()

Datum pg_prewarm ( PG_FUNCTION_ARGS  )

Definition at line 54 of file pg_prewarm.c.

References AccessShareLock, ACL_SELECT, aclcheck_error(), ACLCHECK_OK, buf, CHECK_FOR_INTERRUPTS, PGAlignedBlock::data, ereport, errcode(), errhint(), errmsg(), ERROR, forkname_to_number(), get_rel_name(), get_relkind_objtype(), GetUserId(), PG_ARGISNULL, pg_class_aclcheck(), PG_GETARG_INT64, PG_GETARG_OID, PG_GETARG_TEXT_PP, PG_RETURN_INT64, PrefetchBuffer(), PREWARM_BUFFER, PREWARM_PREFETCH, PREWARM_READ, RBM_NORMAL, RelationData::rd_rel, ReadBufferExtended(), relation_close(), relation_open(), RelationGetNumberOfBlocksInFork(), RelationGetSmgr(), ReleaseBuffer(), smgrexists(), smgrread(), text_to_cstring(), and generate_unaccent_rules::type.

55 {
56  Oid relOid;
57  text *forkName;
58  text *type;
59  int64 first_block;
60  int64 last_block;
61  int64 nblocks;
62  int64 blocks_done = 0;
63  int64 block;
64  Relation rel;
65  ForkNumber forkNumber;
66  char *forkString;
67  char *ttype;
68  PrewarmType ptype;
69  AclResult aclresult;
70 
71  /* Basic sanity checking. */
72  if (PG_ARGISNULL(0))
73  ereport(ERROR,
74  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
75  errmsg("relation cannot be null")));
76  relOid = PG_GETARG_OID(0);
77  if (PG_ARGISNULL(1))
78  ereport(ERROR,
79  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
80  errmsg("prewarm type cannot be null")));
81  type = PG_GETARG_TEXT_PP(1);
82  ttype = text_to_cstring(type);
83  if (strcmp(ttype, "prefetch") == 0)
84  ptype = PREWARM_PREFETCH;
85  else if (strcmp(ttype, "read") == 0)
86  ptype = PREWARM_READ;
87  else if (strcmp(ttype, "buffer") == 0)
88  ptype = PREWARM_BUFFER;
89  else
90  {
91  ereport(ERROR,
92  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
93  errmsg("invalid prewarm type"),
94  errhint("Valid prewarm types are \"prefetch\", \"read\", and \"buffer\".")));
95  PG_RETURN_INT64(0); /* Placate compiler. */
96  }
97  if (PG_ARGISNULL(2))
98  ereport(ERROR,
99  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
100  errmsg("relation fork cannot be null")));
101  forkName = PG_GETARG_TEXT_PP(2);
102  forkString = text_to_cstring(forkName);
103  forkNumber = forkname_to_number(forkString);
104 
105  /* Open relation and check privileges. */
106  rel = relation_open(relOid, AccessShareLock);
107  aclresult = pg_class_aclcheck(relOid, GetUserId(), ACL_SELECT);
108  if (aclresult != ACLCHECK_OK)
109  aclcheck_error(aclresult, get_relkind_objtype(rel->rd_rel->relkind), get_rel_name(relOid));
110 
111  /* Check that the fork exists. */
112  if (!smgrexists(RelationGetSmgr(rel), forkNumber))
113  ereport(ERROR,
114  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
115  errmsg("fork \"%s\" does not exist for this relation",
116  forkString)));
117 
118  /* Validate block numbers, or handle nulls. */
119  nblocks = RelationGetNumberOfBlocksInFork(rel, forkNumber);
120  if (PG_ARGISNULL(3))
121  first_block = 0;
122  else
123  {
124  first_block = PG_GETARG_INT64(3);
125  if (first_block < 0 || first_block >= nblocks)
126  ereport(ERROR,
127  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
128  errmsg("starting block number must be between 0 and %lld",
129  (long long) (nblocks - 1))));
130  }
131  if (PG_ARGISNULL(4))
132  last_block = nblocks - 1;
133  else
134  {
135  last_block = PG_GETARG_INT64(4);
136  if (last_block < 0 || last_block >= nblocks)
137  ereport(ERROR,
138  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
139  errmsg("ending block number must be between 0 and %lld",
140  (long long) (nblocks - 1))));
141  }
142 
143  /* Now we're ready to do the real work. */
144  if (ptype == PREWARM_PREFETCH)
145  {
146 #ifdef USE_PREFETCH
147 
148  /*
149  * In prefetch mode, we just hint the OS to read the blocks, but we
150  * don't know whether it really does it, and we don't wait for it to
151  * finish.
152  *
153  * It would probably be better to pass our prefetch requests in chunks
154  * of a megabyte or maybe even a whole segment at a time, but there's
155  * no practical way to do that at present without a gross modularity
156  * violation, so we just do this.
157  */
158  for (block = first_block; block <= last_block; ++block)
159  {
161  PrefetchBuffer(rel, forkNumber, block);
162  ++blocks_done;
163  }
164 #else
165  ereport(ERROR,
166  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
167  errmsg("prefetch is not supported by this build")));
168 #endif
169  }
170  else if (ptype == PREWARM_READ)
171  {
172  /*
173  * In read mode, we actually read the blocks, but not into shared
174  * buffers. This is more portable than prefetch mode (it works
175  * everywhere) and is synchronous.
176  */
177  for (block = first_block; block <= last_block; ++block)
178  {
180  smgrread(RelationGetSmgr(rel), forkNumber, block, blockbuffer.data);
181  ++blocks_done;
182  }
183  }
184  else if (ptype == PREWARM_BUFFER)
185  {
186  /*
187  * In buffer mode, we actually pull the data into shared_buffers.
188  */
189  for (block = first_block; block <= last_block; ++block)
190  {
191  Buffer buf;
192 
194  buf = ReadBufferExtended(rel, forkNumber, block, RBM_NORMAL, NULL);
195  ReleaseBuffer(buf);
196  ++blocks_done;
197  }
198  }
199 
200  /* Close relation, release lock. */
202 
203  PG_RETURN_INT64(blocks_done);
204 }
PrewarmType
Definition: pg_prewarm.c:32
int errhint(const char *fmt,...)
Definition: elog.c:1156
Oid GetUserId(void)
Definition: miscinit.c:495
#define PG_RETURN_INT64(x)
Definition: fmgr.h:368
Buffer ReadBufferExtended(Relation reln, ForkNumber forkNum, BlockNumber blockNum, ReadBufferMode mode, BufferAccessStrategy strategy)
Definition: bufmgr.c:741
#define AccessShareLock
Definition: lockdefs.h:36
int errcode(int sqlerrcode)
Definition: elog.c:698
void ReleaseBuffer(Buffer buffer)
Definition: bufmgr.c:3768
bool smgrexists(SMgrRelation reln, ForkNumber forknum)
Definition: smgr.c:247
Form_pg_class rd_rel
Definition: rel.h:109
unsigned int Oid
Definition: postgres_ext.h:31
ForkNumber forkname_to_number(const char *forkName)
Definition: relpath.c:50
#define PG_GETARG_TEXT_PP(n)
Definition: fmgr.h:309
void smgrread(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, char *buffer)
Definition: smgr.c:501
void aclcheck_error(AclResult aclerr, ObjectType objtype, const char *objectname)
Definition: aclchk.c:3308
char data[BLCKSZ]
Definition: c.h:1141
#define ERROR
Definition: elog.h:46
static PGAlignedBlock blockbuffer
Definition: pg_prewarm.c:39
Relation relation_open(Oid relationId, LOCKMODE lockmode)
Definition: relation.c:48
static char * buf
Definition: pg_test_fsync.c:68
#define PG_GETARG_OID(n)
Definition: fmgr.h:275
ForkNumber
Definition: relpath.h:40
AclResult
Definition: acl.h:177
#define ACL_SELECT
Definition: parsenodes.h:83
#define ereport(elevel,...)
Definition: elog.h:157
BlockNumber RelationGetNumberOfBlocksInFork(Relation relation, ForkNumber forkNum)
Definition: bufmgr.c:2935
#define PG_ARGISNULL(n)
Definition: fmgr.h:209
void relation_close(Relation relation, LOCKMODE lockmode)
Definition: relation.c:206
static SMgrRelation RelationGetSmgr(Relation rel)
Definition: rel.h:544
AclResult pg_class_aclcheck(Oid table_oid, Oid roleid, AclMode mode)
Definition: aclchk.c:4680
char * text_to_cstring(const text *t)
Definition: varlena.c:222
int errmsg(const char *fmt,...)
Definition: elog.c:909
ObjectType get_relkind_objtype(char relkind)
PrefetchBufferResult PrefetchBuffer(Relation reln, ForkNumber forkNum, BlockNumber blockNum)
Definition: bufmgr.c:587
Definition: c.h:621
#define CHECK_FOR_INTERRUPTS()
Definition: miscadmin.h:120
#define PG_GETARG_INT64(n)
Definition: fmgr.h:283
char * get_rel_name(Oid relid)
Definition: lsyscache.c:1899
int Buffer
Definition: buf.h:23

Variable Documentation

◆ blockbuffer

PGAlignedBlock blockbuffer
static

Definition at line 39 of file pg_prewarm.c.

◆ PG_MODULE_MAGIC

PG_MODULE_MAGIC

Definition at line 28 of file pg_prewarm.c.