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jsonb.h
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1 /*-------------------------------------------------------------------------
2  *
3  * jsonb.h
4  * Declarations for jsonb data type support.
5  *
6  * Copyright (c) 1996-2019, PostgreSQL Global Development Group
7  *
8  * src/include/utils/jsonb.h
9  *
10  *-------------------------------------------------------------------------
11  */
12 #ifndef __JSONB_H__
13 #define __JSONB_H__
14 
15 #include "lib/stringinfo.h"
16 #include "utils/array.h"
17 #include "utils/numeric.h"
18 
19 /* Tokens used when sequentially processing a jsonb value */
20 typedef enum
21 {
31 
32 /* Strategy numbers for GIN index opclasses */
33 #define JsonbContainsStrategyNumber 7
34 #define JsonbExistsStrategyNumber 9
35 #define JsonbExistsAnyStrategyNumber 10
36 #define JsonbExistsAllStrategyNumber 11
37 #define JsonbJsonpathExistsStrategyNumber 15
38 #define JsonbJsonpathPredicateStrategyNumber 16
39 
40 
41 /*
42  * In the standard jsonb_ops GIN opclass for jsonb, we choose to index both
43  * keys and values. The storage format is text. The first byte of the text
44  * string distinguishes whether this is a key (always a string), null value,
45  * boolean value, numeric value, or string value. However, array elements
46  * that are strings are marked as though they were keys; this imprecision
47  * supports the definition of the "exists" operator, which treats array
48  * elements like keys. The remainder of the text string is empty for a null
49  * value, "t" or "f" for a boolean value, a normalized print representation of
50  * a numeric value, or the text of a string value. However, if the length of
51  * this text representation would exceed JGIN_MAXLENGTH bytes, we instead hash
52  * the text representation and store an 8-hex-digit representation of the
53  * uint32 hash value, marking the prefix byte with an additional bit to
54  * distinguish that this has happened. Hashing long strings saves space and
55  * ensures that we won't overrun the maximum entry length for a GIN index.
56  * (But JGIN_MAXLENGTH is quite a bit shorter than GIN's limit. It's chosen
57  * to ensure that the on-disk text datum will have a short varlena header.)
58  * Note that when any hashed item appears in a query, we must recheck index
59  * matches against the heap tuple; currently, this costs nothing because we
60  * must always recheck for other reasons.
61  */
62 #define JGINFLAG_KEY 0x01 /* key (or string array element) */
63 #define JGINFLAG_NULL 0x02 /* null value */
64 #define JGINFLAG_BOOL 0x03 /* boolean value */
65 #define JGINFLAG_NUM 0x04 /* numeric value */
66 #define JGINFLAG_STR 0x05 /* string value (if not an array element) */
67 #define JGINFLAG_HASHED 0x10 /* OR'd into flag if value was hashed */
68 #define JGIN_MAXLENGTH 125 /* max length of text part before hashing */
69 
70 /* Convenience macros */
71 #define DatumGetJsonbP(d) ((Jsonb *) PG_DETOAST_DATUM(d))
72 #define DatumGetJsonbPCopy(d) ((Jsonb *) PG_DETOAST_DATUM_COPY(d))
73 #define JsonbPGetDatum(p) PointerGetDatum(p)
74 #define PG_GETARG_JSONB_P(x) DatumGetJsonbP(PG_GETARG_DATUM(x))
75 #define PG_GETARG_JSONB_P_COPY(x) DatumGetJsonbPCopy(PG_GETARG_DATUM(x))
76 #define PG_RETURN_JSONB_P(x) PG_RETURN_POINTER(x)
77 
78 typedef struct JsonbPair JsonbPair;
79 typedef struct JsonbValue JsonbValue;
80 
81 /*
82  * Jsonbs are varlena objects, so must meet the varlena convention that the
83  * first int32 of the object contains the total object size in bytes. Be sure
84  * to use VARSIZE() and SET_VARSIZE() to access it, though!
85  *
86  * Jsonb is the on-disk representation, in contrast to the in-memory JsonbValue
87  * representation. Often, JsonbValues are just shims through which a Jsonb
88  * buffer is accessed, but they can also be deep copied and passed around.
89  *
90  * Jsonb is a tree structure. Each node in the tree consists of a JEntry
91  * header and a variable-length content (possibly of zero size). The JEntry
92  * header indicates what kind of a node it is, e.g. a string or an array,
93  * and provides the length of its variable-length portion.
94  *
95  * The JEntry and the content of a node are not stored physically together.
96  * Instead, the container array or object has an array that holds the JEntrys
97  * of all the child nodes, followed by their variable-length portions.
98  *
99  * The root node is an exception; it has no parent array or object that could
100  * hold its JEntry. Hence, no JEntry header is stored for the root node. It
101  * is implicitly known that the root node must be an array or an object,
102  * so we can get away without the type indicator as long as we can distinguish
103  * the two. For that purpose, both an array and an object begin with a uint32
104  * header field, which contains an JB_FOBJECT or JB_FARRAY flag. When a naked
105  * scalar value needs to be stored as a Jsonb value, what we actually store is
106  * an array with one element, with the flags in the array's header field set
107  * to JB_FSCALAR | JB_FARRAY.
108  *
109  * Overall, the Jsonb struct requires 4-bytes alignment. Within the struct,
110  * the variable-length portion of some node types is aligned to a 4-byte
111  * boundary, while others are not. When alignment is needed, the padding is
112  * in the beginning of the node that requires it. For example, if a numeric
113  * node is stored after a string node, so that the numeric node begins at
114  * offset 3, the variable-length portion of the numeric node will begin with
115  * one padding byte so that the actual numeric data is 4-byte aligned.
116  */
117 
118 /*
119  * JEntry format.
120  *
121  * The least significant 28 bits store either the data length of the entry,
122  * or its end+1 offset from the start of the variable-length portion of the
123  * containing object. The next three bits store the type of the entry, and
124  * the high-order bit tells whether the least significant bits store a length
125  * or an offset.
126  *
127  * The reason for the offset-or-length complication is to compromise between
128  * access speed and data compressibility. In the initial design each JEntry
129  * always stored an offset, but this resulted in JEntry arrays with horrible
130  * compressibility properties, so that TOAST compression of a JSONB did not
131  * work well. Storing only lengths would greatly improve compressibility,
132  * but it makes random access into large arrays expensive (O(N) not O(1)).
133  * So what we do is store an offset in every JB_OFFSET_STRIDE'th JEntry and
134  * a length in the rest. This results in reasonably compressible data (as
135  * long as the stride isn't too small). We may have to examine as many as
136  * JB_OFFSET_STRIDE JEntrys in order to find out the offset or length of any
137  * given item, but that's still O(1) no matter how large the container is.
138  *
139  * We could avoid eating a flag bit for this purpose if we were to store
140  * the stride in the container header, or if we were willing to treat the
141  * stride as an unchangeable constant. Neither of those options is very
142  * attractive though.
143  */
144 typedef uint32 JEntry;
145 
146 #define JENTRY_OFFLENMASK 0x0FFFFFFF
147 #define JENTRY_TYPEMASK 0x70000000
148 #define JENTRY_HAS_OFF 0x80000000
149 
150 /* values stored in the type bits */
151 #define JENTRY_ISSTRING 0x00000000
152 #define JENTRY_ISNUMERIC 0x10000000
153 #define JENTRY_ISBOOL_FALSE 0x20000000
154 #define JENTRY_ISBOOL_TRUE 0x30000000
155 #define JENTRY_ISNULL 0x40000000
156 #define JENTRY_ISCONTAINER 0x50000000 /* array or object */
157 
158 /* Access macros. Note possible multiple evaluations */
159 #define JBE_OFFLENFLD(je_) ((je_) & JENTRY_OFFLENMASK)
160 #define JBE_HAS_OFF(je_) (((je_) & JENTRY_HAS_OFF) != 0)
161 #define JBE_ISSTRING(je_) (((je_) & JENTRY_TYPEMASK) == JENTRY_ISSTRING)
162 #define JBE_ISNUMERIC(je_) (((je_) & JENTRY_TYPEMASK) == JENTRY_ISNUMERIC)
163 #define JBE_ISCONTAINER(je_) (((je_) & JENTRY_TYPEMASK) == JENTRY_ISCONTAINER)
164 #define JBE_ISNULL(je_) (((je_) & JENTRY_TYPEMASK) == JENTRY_ISNULL)
165 #define JBE_ISBOOL_TRUE(je_) (((je_) & JENTRY_TYPEMASK) == JENTRY_ISBOOL_TRUE)
166 #define JBE_ISBOOL_FALSE(je_) (((je_) & JENTRY_TYPEMASK) == JENTRY_ISBOOL_FALSE)
167 #define JBE_ISBOOL(je_) (JBE_ISBOOL_TRUE(je_) || JBE_ISBOOL_FALSE(je_))
168 
169 /* Macro for advancing an offset variable to the next JEntry */
170 #define JBE_ADVANCE_OFFSET(offset, je) \
171  do { \
172  JEntry je_ = (je); \
173  if (JBE_HAS_OFF(je_)) \
174  (offset) = JBE_OFFLENFLD(je_); \
175  else \
176  (offset) += JBE_OFFLENFLD(je_); \
177  } while(0)
178 
179 /*
180  * We store an offset, not a length, every JB_OFFSET_STRIDE children.
181  * Caution: this macro should only be referenced when creating a JSONB
182  * value. When examining an existing value, pay attention to the HAS_OFF
183  * bits instead. This allows changes in the offset-placement heuristic
184  * without breaking on-disk compatibility.
185  */
186 #define JB_OFFSET_STRIDE 32
187 
188 /*
189  * A jsonb array or object node, within a Jsonb Datum.
190  *
191  * An array has one child for each element, stored in array order.
192  *
193  * An object has two children for each key/value pair. The keys all appear
194  * first, in key sort order; then the values appear, in an order matching the
195  * key order. This arrangement keeps the keys compact in memory, making a
196  * search for a particular key more cache-friendly.
197  */
198 typedef struct JsonbContainer
199 {
200  uint32 header; /* number of elements or key/value pairs, and
201  * flags */
202  JEntry children[FLEXIBLE_ARRAY_MEMBER];
203 
204  /* the data for each child node follows. */
206 
207 /* flags for the header-field in JsonbContainer */
208 #define JB_CMASK 0x0FFFFFFF /* mask for count field */
209 #define JB_FSCALAR 0x10000000 /* flag bits */
210 #define JB_FOBJECT 0x20000000
211 #define JB_FARRAY 0x40000000
212 
213 /* convenience macros for accessing a JsonbContainer struct */
214 #define JsonContainerSize(jc) ((jc)->header & JB_CMASK)
215 #define JsonContainerIsScalar(jc) (((jc)->header & JB_FSCALAR) != 0)
216 #define JsonContainerIsObject(jc) (((jc)->header & JB_FOBJECT) != 0)
217 #define JsonContainerIsArray(jc) (((jc)->header & JB_FARRAY) != 0)
218 
219 /* The top-level on-disk format for a jsonb datum. */
220 typedef struct
221 {
222  int32 vl_len_; /* varlena header (do not touch directly!) */
224 } Jsonb;
225 
226 /* convenience macros for accessing the root container in a Jsonb datum */
227 #define JB_ROOT_COUNT(jbp_) (*(uint32 *) VARDATA(jbp_) & JB_CMASK)
228 #define JB_ROOT_IS_SCALAR(jbp_) ((*(uint32 *) VARDATA(jbp_) & JB_FSCALAR) != 0)
229 #define JB_ROOT_IS_OBJECT(jbp_) ((*(uint32 *) VARDATA(jbp_) & JB_FOBJECT) != 0)
230 #define JB_ROOT_IS_ARRAY(jbp_) ((*(uint32 *) VARDATA(jbp_) & JB_FARRAY) != 0)
231 
232 
234 {
235  /* Scalar types */
236  jbvNull = 0x0,
240  /* Composite types */
241  jbvArray = 0x10,
243  /* Binary (i.e. struct Jsonb) jbvArray/jbvObject */
245 };
246 
247 /*
248  * JsonbValue: In-memory representation of Jsonb. This is a convenient
249  * deserialized representation, that can easily support using the "val"
250  * union across underlying types during manipulation. The Jsonb on-disk
251  * representation has various alignment considerations.
252  */
254 {
255  enum jbvType type; /* Influences sort order */
256 
257  union
258  {
260  bool boolean;
261  struct
262  {
263  int len;
264  char *val; /* Not necessarily null-terminated */
265  } string; /* String primitive type */
266 
267  struct
268  {
269  int nElems;
271  bool rawScalar; /* Top-level "raw scalar" array? */
272  } array; /* Array container type */
273 
274  struct
275  {
276  int nPairs; /* 1 pair, 2 elements */
278  } object; /* Associative container type */
279 
280  struct
281  {
282  int len;
284  } binary; /* Array or object, in on-disk format */
285  } val;
286 };
287 
288 #define IsAJsonbScalar(jsonbval) ((jsonbval)->type >= jbvNull && \
289  (jsonbval)->type <= jbvBool)
290 
291 /*
292  * Key/value pair within an Object.
293  *
294  * This struct type is only used briefly while constructing a Jsonb; it is
295  * *not* the on-disk representation.
296  *
297  * Pairs with duplicate keys are de-duplicated. We store the originally
298  * observed pair ordering for the purpose of removing duplicates in a
299  * well-defined way (which is "last observed wins").
300  */
301 struct JsonbPair
302 {
303  JsonbValue key; /* Must be a jbvString */
304  JsonbValue value; /* May be of any type */
305  uint32 order; /* Pair's index in original sequence */
306 };
307 
308 /* Conversion state used when parsing Jsonb from text, or for type coercion */
309 typedef struct JsonbParseState
310 {
315 
316 /*
317  * JsonbIterator holds details of the type for each iteration. It also stores a
318  * Jsonb varlena buffer, which can be directly accessed in some contexts.
319  */
320 typedef enum
321 {
328 
329 typedef struct JsonbIterator
330 {
331  /* Container being iterated */
333  uint32 nElems; /* Number of elements in children array (will
334  * be nPairs for objects) */
335  bool isScalar; /* Pseudo-array scalar value? */
336  JEntry *children; /* JEntrys for child nodes */
337  /* Data proper. This points to the beginning of the variable-length data */
338  char *dataProper;
339 
340  /* Current item in buffer (up to nElems) */
341  int curIndex;
342 
343  /* Data offset corresponding to current item */
345 
346  /*
347  * If the container is an object, we want to return keys and values
348  * alternately; so curDataOffset points to the current key, and
349  * curValueOffset points to the current value.
350  */
352 
353  /* Private state */
355 
357 } JsonbIterator;
358 
359 
360 /* Support functions */
361 extern uint32 getJsonbOffset(const JsonbContainer *jc, int index);
362 extern uint32 getJsonbLength(const JsonbContainer *jc, int index);
365  uint32 flags,
366  JsonbValue *key);
368  const char *keyVal, int keyLen,
369  JsonbValue *res);
371  uint32 i);
372 extern JsonbValue *pushJsonbValue(JsonbParseState **pstate,
373  JsonbIteratorToken seq, JsonbValue *jbval);
376  bool skipNested);
378 extern bool JsonbDeepContains(JsonbIterator **val,
379  JsonbIterator **mContained);
380 extern void JsonbHashScalarValue(const JsonbValue *scalarVal, uint32 *hash);
381 extern void JsonbHashScalarValueExtended(const JsonbValue *scalarVal,
382  uint64 *hash, uint64 seed);
383 
384 /* jsonb.c support functions */
385 extern char *JsonbToCString(StringInfo out, JsonbContainer *in,
386  int estimated_len);
387 extern char *JsonbToCStringIndent(StringInfo out, JsonbContainer *in,
388  int estimated_len);
389 extern bool JsonbExtractScalar(JsonbContainer *jbc, JsonbValue *res);
390 extern const char *JsonbTypeName(JsonbValue *jb);
391 
392 
393 #endif /* __JSONB_H__ */
char * JsonbToCStringIndent(StringInfo out, JsonbContainer *in, int estimated_len)
Definition: jsonb.c:451
JsonbIterState state
Definition: jsonb.h:354
uint32 order
Definition: jsonb.h:305
JEntry children[FLEXIBLE_ARRAY_MEMBER]
Definition: jsonb.h:202
bool JsonbExtractScalar(JsonbContainer *jbc, JsonbValue *res)
Definition: jsonb.c:1874
JEntry * children
Definition: jsonb.h:336
struct JsonbParseState JsonbParseState
Definition: jsonb.h:220
JsonbIterator * JsonbIteratorInit(JsonbContainer *container)
Definition: jsonb_util.c:752
Numeric numeric
Definition: jsonb.h:259
jbvType
Definition: jsonb.h:233
JsonbContainer * data
Definition: jsonb.h:283
char * val
Definition: jsonb.h:264
Definition: jsonb.h:239
int compareJsonbContainers(JsonbContainer *a, JsonbContainer *b)
Definition: jsonb_util.c:180
uint32 getJsonbLength(const JsonbContainer *jc, int index)
Definition: jsonb_util.c:148
Definition: jsonb.h:22
Definition: jsonb.h:236
bool boolean
Definition: jsonb.h:260
char * JsonbToCString(StringInfo out, JsonbContainer *in, int estimated_len)
Definition: jsonb.c:442
struct JsonbContainer JsonbContainer
JsonbValue * findJsonbValueFromContainer(JsonbContainer *sheader, uint32 flags, JsonbValue *key)
Definition: jsonb_util.c:329
struct JsonbParseState * next
Definition: jsonb.h:313
int len
Definition: jsonb.h:263
signed int int32
Definition: c.h:346
Definition: type.h:89
JsonbValue * getIthJsonbValueFromContainer(JsonbContainer *sheader, uint32 i)
Definition: jsonb_util.c:453
void JsonbHashScalarValueExtended(const JsonbValue *scalarVal, uint64 *hash, uint64 seed)
Definition: jsonb_util.c:1294
uint32 curDataOffset
Definition: jsonb.h:344
void JsonbHashScalarValue(const JsonbValue *scalarVal, uint32 *hash)
Definition: jsonb_util.c:1251
bool rawScalar
Definition: jsonb.h:271
struct JsonbIterator JsonbIterator
JsonbContainer * container
Definition: jsonb.h:332
char string[11]
Definition: preproc-type.c:46
JsonbValue * elems
Definition: jsonb.h:270
unsigned int uint32
Definition: c.h:358
JsonbValue key
Definition: jsonb.h:303
Definition: jsonb.h:23
JsonbIteratorToken
Definition: jsonb.h:20
JsonbPair * pairs
Definition: jsonb.h:277
JsonbContainer root
Definition: jsonb.h:223
uint32 header
Definition: jsonb.h:200
JsonbValue contVal
Definition: jsonb.h:311
bool isScalar
Definition: jsonb.h:335
Jsonb * JsonbValueToJsonb(JsonbValue *val)
Definition: jsonb_util.c:81
JsonbIteratorToken JsonbIteratorNext(JsonbIterator **it, JsonbValue *val, bool skipNested)
Definition: jsonb_util.c:788
int nPairs
Definition: jsonb.h:276
int curIndex
Definition: jsonb.h:341
struct JsonbIterator * parent
Definition: jsonb.h:356
int nElems
Definition: jsonb.h:269
uint32 JEntry
Definition: jsonb.h:144
JsonbValue * getKeyJsonValueFromContainer(JsonbContainer *container, const char *keyVal, int keyLen, JsonbValue *res)
Definition: jsonb_util.c:383
int32 vl_len_
Definition: jsonb.h:222
size_t Size
Definition: c.h:466
char * dataProper
Definition: jsonb.h:338
bool JsonbDeepContains(JsonbIterator **val, JsonbIterator **mContained)
Definition: jsonb_util.c:997
JsonbValue value
Definition: jsonb.h:304
uint32 curValueOffset
Definition: jsonb.h:351
int i
const char * JsonbTypeName(JsonbValue *jb)
Definition: jsonb.c:191
uint32 nElems
Definition: jsonb.h:333
JsonbValue * pushJsonbValue(JsonbParseState **pstate, JsonbIteratorToken seq, JsonbValue *jbval)
Definition: jsonb_util.c:551
JsonbIterState
Definition: jsonb.h:320
static unsigned hash(unsigned *uv, int n)
Definition: rege_dfa.c:541
long val
Definition: informix.c:684
Definition: jsonb.h:25
uint32 getJsonbOffset(const JsonbContainer *jc, int index)
Definition: jsonb_util.c:123