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expandedrecord.h
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1 /*-------------------------------------------------------------------------
2  *
3  * expandedrecord.h
4  * Declarations for composite expanded objects.
5  *
6  * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
7  * Portions Copyright (c) 1994, Regents of the University of California
8  *
9  * src/include/utils/expandedrecord.h
10  *
11  *-------------------------------------------------------------------------
12  */
13 #ifndef EXPANDEDRECORD_H
14 #define EXPANDEDRECORD_H
15 
16 #include "access/htup.h"
17 #include "access/tupdesc.h"
18 #include "fmgr.h"
19 #include "utils/expandeddatum.h"
20 
21 
22 /*
23  * An expanded record is contained within a private memory context (as
24  * all expanded objects must be) and has a control structure as below.
25  *
26  * The expanded record might contain a regular "flat" tuple if that was the
27  * original input and we've not modified it. Otherwise, the contents are
28  * represented by Datum/isnull arrays plus type information. We could also
29  * have both forms, if we've deconstructed the original tuple for access
30  * purposes but not yet changed it. For pass-by-reference field types, the
31  * Datums would point into the flat tuple in this situation. Once we start
32  * modifying tuple fields, new pass-by-ref fields are separately palloc'd
33  * within the memory context.
34  *
35  * It's possible to build an expanded record that references a "flat" tuple
36  * stored externally, if the caller can guarantee that that tuple will not
37  * change for the lifetime of the expanded record. (This frammish is mainly
38  * meant to avoid unnecessary data copying in trigger functions.)
39  */
40 #define ER_MAGIC 1384727874 /* ID for debugging crosschecks */
41 
42 typedef struct ExpandedRecordHeader
43 {
44  /* Standard header for expanded objects */
46 
47  /* Magic value identifying an expanded record (for debugging only) */
48  int er_magic;
49 
50  /* Assorted flag bits */
51  int flags;
52 #define ER_FLAG_FVALUE_VALID 0x0001 /* fvalue is up to date? */
53 #define ER_FLAG_FVALUE_ALLOCED 0x0002 /* fvalue is local storage? */
54 #define ER_FLAG_DVALUES_VALID 0x0004 /* dvalues/dnulls are up to date? */
55 #define ER_FLAG_DVALUES_ALLOCED 0x0008 /* any field values local storage? */
56 #define ER_FLAG_HAVE_EXTERNAL 0x0010 /* any field values are external? */
57 #define ER_FLAG_TUPDESC_ALLOCED 0x0020 /* tupdesc is local storage? */
58 #define ER_FLAG_IS_DOMAIN 0x0040 /* er_decltypeid is domain? */
59 #define ER_FLAG_IS_DUMMY 0x0080 /* this header is dummy (see below) */
60 /* flag bits that are not to be cleared when replacing tuple data: */
61 #define ER_FLAGS_NON_DATA \
62  (ER_FLAG_TUPDESC_ALLOCED | ER_FLAG_IS_DOMAIN | ER_FLAG_IS_DUMMY)
63 
64  /* Declared type of the record variable (could be a domain type) */
66 
67  /*
68  * Actual composite type/typmod; never a domain (if ER_FLAG_IS_DOMAIN,
69  * these identify the composite base type). These will match
70  * er_tupdesc->tdtypeid/tdtypmod, as well as the header fields of
71  * composite datums made from or stored in this expanded record.
72  */
73  Oid er_typeid; /* type OID of the composite type */
74  int32 er_typmod; /* typmod of the composite type */
75 
76  /*
77  * Tuple descriptor, if we have one, else NULL. This may point to a
78  * reference-counted tupdesc originally belonging to the typcache, in
79  * which case we use a memory context reset callback to release the
80  * refcount. It can also be locally allocated in this object's private
81  * context (in which case ER_FLAG_TUPDESC_ALLOCED is set).
82  */
84 
85  /*
86  * Unique-within-process identifier for the tupdesc (see typcache.h). This
87  * field will never be equal to INVALID_TUPLEDESC_IDENTIFIER.
88  */
89  uint64 er_tupdesc_id;
90 
91  /*
92  * If we have a Datum-array representation of the record, it's kept here;
93  * else ER_FLAG_DVALUES_VALID is not set, and dvalues/dnulls may be NULL
94  * if they've not yet been allocated. If allocated, the dvalues and
95  * dnulls arrays are palloc'd within the object private context, and are
96  * of length matching er_tupdesc->natts. For pass-by-ref field types,
97  * dvalues entries might point either into the fstartptr..fendptr area, or
98  * to separately palloc'd chunks.
99  */
100  Datum *dvalues; /* array of Datums */
101  bool *dnulls; /* array of is-null flags for Datums */
102  int nfields; /* length of above arrays */
103 
104  /*
105  * flat_size is the current space requirement for the flat equivalent of
106  * the expanded record, if known; otherwise it's 0. We store this to make
107  * consecutive calls of get_flat_size cheap. If flat_size is not 0, the
108  * component values data_len, hoff, and hasnull must be valid too.
109  */
111 
112  Size data_len; /* data len within flat_size */
113  int hoff; /* header offset */
114  bool hasnull; /* null bitmap needed? */
115 
116  /*
117  * fvalue points to the flat representation if we have one, else it is
118  * NULL. If the flat representation is valid (up to date) then
119  * ER_FLAG_FVALUE_VALID is set. Even if we've outdated the flat
120  * representation due to changes of user fields, it can still be used to
121  * fetch system column values. If we have a flat representation then
122  * fstartptr/fendptr point to the start and end+1 of its data area; this
123  * is so that we can tell which Datum pointers point into the flat
124  * representation rather than being pointers to separately palloc'd data.
125  */
126  HeapTuple fvalue; /* might or might not be private storage */
127  char *fstartptr; /* start of its data area */
128  char *fendptr; /* end+1 of its data area */
129 
130  /* Some operations on the expanded record need a short-lived context */
131  MemoryContext er_short_term_cxt; /* short-term memory context */
132 
133  /* Working state for domain checking, used if ER_FLAG_IS_DOMAIN is set */
134  struct ExpandedRecordHeader *er_dummy_header; /* dummy record header */
135  void *er_domaininfo; /* cache space for domain_check() */
136 
137  /* Callback info (it's active if er_mcb.arg is not NULL) */
140 
141 /* fmgr macros for expanded record objects */
142 #define PG_GETARG_EXPANDED_RECORD(n) DatumGetExpandedRecord(PG_GETARG_DATUM(n))
143 #define ExpandedRecordGetDatum(erh) EOHPGetRWDatum(&(erh)->hdr)
144 #define ExpandedRecordGetRODatum(erh) EOHPGetRODatum(&(erh)->hdr)
145 #define PG_RETURN_EXPANDED_RECORD(x) PG_RETURN_DATUM(ExpandedRecordGetDatum(x))
146 
147 /* assorted other macros */
148 #define ExpandedRecordIsEmpty(erh) \
149  (((erh)->flags & (ER_FLAG_DVALUES_VALID | ER_FLAG_FVALUE_VALID)) == 0)
150 #define ExpandedRecordIsDomain(erh) \
151  (((erh)->flags & ER_FLAG_IS_DOMAIN) != 0)
152 
153 /* this can substitute for TransferExpandedObject() when we already have erh */
154 #define TransferExpandedRecord(erh, cxt) \
155  MemoryContextSetParent((erh)->hdr.eoh_context, cxt)
156 
157 /* information returned by expanded_record_lookup_field() */
159 {
160  int fnumber; /* field's attr number in record */
161  Oid ftypeid; /* field's type/typmod info */
163  Oid fcollation; /* field's collation if any */
165 
166 /*
167  * prototypes for functions defined in expandedrecord.c
168  */
170  MemoryContext parentcontext);
172  MemoryContext parentcontext);
174  MemoryContext parentcontext);
176  HeapTuple tuple, bool copy, bool expand_external);
177 extern Datum make_expanded_record_from_datum(Datum recorddatum,
178  MemoryContext parentcontext);
184  const char *fieldname,
185  ExpandedRecordFieldInfo *finfo);
187  bool *isnull);
189  int fnumber,
190  Datum newValue, bool isnull,
191  bool expand_external,
192  bool check_constraints);
194  const Datum *newValues, const bool *isnulls,
195  bool expand_external);
196 
197 /* outside code should never call expanded_record_set_field_internal as such */
198 #define expanded_record_set_field(erh, fnumber, newValue, isnull, expand_external) \
199  expanded_record_set_field_internal(erh, fnumber, newValue, isnull, expand_external, true)
200 
201 /*
202  * Inline-able fast cases. The expanded_record_fetch_xxx functions above
203  * handle the general cases.
204  */
205 
206 /* Get the tupdesc for the expanded record's actual type */
207 static inline TupleDesc
209 {
210  if (likely(erh->er_tupdesc != NULL))
211  return erh->er_tupdesc;
212  else
213  return expanded_record_fetch_tupdesc(erh);
214 }
215 
216 /* Get value of record field */
217 static inline Datum
219  bool *isnull)
220 {
221  if ((erh->flags & ER_FLAG_DVALUES_VALID) &&
222  likely(fnumber > 0 && fnumber <= erh->nfields))
223  {
224  *isnull = erh->dnulls[fnumber - 1];
225  return erh->dvalues[fnumber - 1];
226  }
227  else
228  return expanded_record_fetch_field(erh, fnumber, isnull);
229 }
230 
231 #endif /* EXPANDEDRECORD_H */
ExpandedRecordHeader * make_expanded_record_from_exprecord(ExpandedRecordHeader *olderh, MemoryContext parentcontext)
#define likely(x)
Definition: c.h:207
static Datum expanded_record_get_field(ExpandedRecordHeader *erh, int fnumber, bool *isnull)
ExpandedRecordHeader * make_expanded_record_from_tupdesc(TupleDesc tupdesc, MemoryContext parentcontext)
ExpandedRecordHeader * DatumGetExpandedRecord(Datum d)
unsigned int Oid
Definition: postgres_ext.h:31
ExpandedObjectHeader hdr
ExpandedRecordHeader * make_expanded_record_from_typeid(Oid type_id, int32 typmod, MemoryContext parentcontext)
MemoryContext er_short_term_cxt
signed int int32
Definition: c.h:347
void expanded_record_set_field_internal(ExpandedRecordHeader *erh, int fnumber, Datum newValue, bool isnull, bool expand_external, bool check_constraints)
#define ER_FLAG_DVALUES_VALID
HeapTuple expanded_record_get_tuple(ExpandedRecordHeader *erh)
bool expanded_record_lookup_field(ExpandedRecordHeader *erh, const char *fieldname, ExpandedRecordFieldInfo *finfo)
void deconstruct_expanded_record(ExpandedRecordHeader *erh)
static TupleDesc expanded_record_get_tupdesc(ExpandedRecordHeader *erh)
MemoryContextCallback er_mcb
uintptr_t Datum
Definition: postgres.h:367
void expanded_record_set_tuple(ExpandedRecordHeader *erh, HeapTuple tuple, bool copy, bool expand_external)
Datum expanded_record_fetch_field(ExpandedRecordHeader *erh, int fnumber, bool *isnull)
size_t Size
Definition: c.h:467
Datum make_expanded_record_from_datum(Datum recorddatum, MemoryContext parentcontext)
struct ExpandedRecordFieldInfo ExpandedRecordFieldInfo
void expanded_record_set_fields(ExpandedRecordHeader *erh, const Datum *newValues, const bool *isnulls, bool expand_external)
struct ExpandedRecordHeader ExpandedRecordHeader
struct ExpandedRecordHeader * er_dummy_header
TupleDesc expanded_record_fetch_tupdesc(ExpandedRecordHeader *erh)