/*------------------------------------------------------------------------- * * jsonb.h * Declarations for jsonb data type support. * * Copyright (c) 1996-2022, PostgreSQL Global Development Group * * src/include/utils/jsonb.h * *------------------------------------------------------------------------- */ #ifndef __JSONB_H__ #define __JSONB_H__ #include "lib/stringinfo.h" #include "utils/array.h" #include "utils/numeric.h" /* Tokens used when sequentially processing a jsonb value */ typedef enum { WJB_DONE, WJB_KEY, WJB_VALUE, WJB_ELEM, WJB_BEGIN_ARRAY, WJB_END_ARRAY, WJB_BEGIN_OBJECT, WJB_END_OBJECT } JsonbIteratorToken; /* Strategy numbers for GIN index opclasses */ #define JsonbContainsStrategyNumber 7 #define JsonbExistsStrategyNumber 9 #define JsonbExistsAnyStrategyNumber 10 #define JsonbExistsAllStrategyNumber 11 #define JsonbJsonpathExistsStrategyNumber 15 #define JsonbJsonpathPredicateStrategyNumber 16 /* * In the standard jsonb_ops GIN opclass for jsonb, we choose to index both * keys and values. The storage format is text. The first byte of the text * string distinguishes whether this is a key (always a string), null value, * boolean value, numeric value, or string value. However, array elements * that are strings are marked as though they were keys; this imprecision * supports the definition of the "exists" operator, which treats array * elements like keys. The remainder of the text string is empty for a null * value, "t" or "f" for a boolean value, a normalized print representation of * a numeric value, or the text of a string value. However, if the length of * this text representation would exceed JGIN_MAXLENGTH bytes, we instead hash * the text representation and store an 8-hex-digit representation of the * uint32 hash value, marking the prefix byte with an additional bit to * distinguish that this has happened. Hashing long strings saves space and * ensures that we won't overrun the maximum entry length for a GIN index. * (But JGIN_MAXLENGTH is quite a bit shorter than GIN's limit. It's chosen * to ensure that the on-disk text datum will have a short varlena header.) * Note that when any hashed item appears in a query, we must recheck index * matches against the heap tuple; currently, this costs nothing because we * must always recheck for other reasons. */ #define JGINFLAG_KEY 0x01 /* key (or string array element) */ #define JGINFLAG_NULL 0x02 /* null value */ #define JGINFLAG_BOOL 0x03 /* boolean value */ #define JGINFLAG_NUM 0x04 /* numeric value */ #define JGINFLAG_STR 0x05 /* string value (if not an array element) */ #define JGINFLAG_HASHED 0x10 /* OR'd into flag if value was hashed */ #define JGIN_MAXLENGTH 125 /* max length of text part before hashing */ /* Convenience macros */ #define DatumGetJsonbP(d) ((Jsonb *) PG_DETOAST_DATUM(d)) #define DatumGetJsonbPCopy(d) ((Jsonb *) PG_DETOAST_DATUM_COPY(d)) #define JsonbPGetDatum(p) PointerGetDatum(p) #define PG_GETARG_JSONB_P(x) DatumGetJsonbP(PG_GETARG_DATUM(x)) #define PG_GETARG_JSONB_P_COPY(x) DatumGetJsonbPCopy(PG_GETARG_DATUM(x)) #define PG_RETURN_JSONB_P(x) PG_RETURN_POINTER(x) typedef struct JsonbPair JsonbPair; typedef struct JsonbValue JsonbValue; /* * Jsonbs are varlena objects, so must meet the varlena convention that the * first int32 of the object contains the total object size in bytes. Be sure * to use VARSIZE() and SET_VARSIZE() to access it, though! * * Jsonb is the on-disk representation, in contrast to the in-memory JsonbValue * representation. Often, JsonbValues are just shims through which a Jsonb * buffer is accessed, but they can also be deep copied and passed around. * * Jsonb is a tree structure. Each node in the tree consists of a JEntry * header and a variable-length content (possibly of zero size). The JEntry * header indicates what kind of a node it is, e.g. a string or an array, * and provides the length of its variable-length portion. * * The JEntry and the content of a node are not stored physically together. * Instead, the container array or object has an array that holds the JEntrys * of all the child nodes, followed by their variable-length portions. * * The root node is an exception; it has no parent array or object that could * hold its JEntry. Hence, no JEntry header is stored for the root node. It * is implicitly known that the root node must be an array or an object, * so we can get away without the type indicator as long as we can distinguish * the two. For that purpose, both an array and an object begin with a uint32 * header field, which contains an JB_FOBJECT or JB_FARRAY flag. When a naked * scalar value needs to be stored as a Jsonb value, what we actually store is * an array with one element, with the flags in the array's header field set * to JB_FSCALAR | JB_FARRAY. * * Overall, the Jsonb struct requires 4-bytes alignment. Within the struct, * the variable-length portion of some node types is aligned to a 4-byte * boundary, while others are not. When alignment is needed, the padding is * in the beginning of the node that requires it. For example, if a numeric * node is stored after a string node, so that the numeric node begins at * offset 3, the variable-length portion of the numeric node will begin with * one padding byte so that the actual numeric data is 4-byte aligned. */ /* * JEntry format. * * The least significant 28 bits store either the data length of the entry, * or its end+1 offset from the start of the variable-length portion of the * containing object. The next three bits store the type of the entry, and * the high-order bit tells whether the least significant bits store a length * or an offset. * * The reason for the offset-or-length complication is to compromise between * access speed and data compressibility. In the initial design each JEntry * always stored an offset, but this resulted in JEntry arrays with horrible * compressibility properties, so that TOAST compression of a JSONB did not * work well. Storing only lengths would greatly improve compressibility, * but it makes random access into large arrays expensive (O(N) not O(1)). * So what we do is store an offset in every JB_OFFSET_STRIDE'th JEntry and * a length in the rest. This results in reasonably compressible data (as * long as the stride isn't too small). We may have to examine as many as * JB_OFFSET_STRIDE JEntrys in order to find out the offset or length of any * given item, but that's still O(1) no matter how large the container is. * * We could avoid eating a flag bit for this purpose if we were to store * the stride in the container header, or if we were willing to treat the * stride as an unchangeable constant. Neither of those options is very * attractive though. */ typedef uint32 JEntry; #define JENTRY_OFFLENMASK 0x0FFFFFFF #define JENTRY_TYPEMASK 0x70000000 #define JENTRY_HAS_OFF 0x80000000 /* values stored in the type bits */ #define JENTRY_ISSTRING 0x00000000 #define JENTRY_ISNUMERIC 0x10000000 #define JENTRY_ISBOOL_FALSE 0x20000000 #define JENTRY_ISBOOL_TRUE 0x30000000 #define JENTRY_ISNULL 0x40000000 #define JENTRY_ISCONTAINER 0x50000000 /* array or object */ /* Access macros. Note possible multiple evaluations */ #define JBE_OFFLENFLD(je_) ((je_) & JENTRY_OFFLENMASK) #define JBE_HAS_OFF(je_) (((je_) & JENTRY_HAS_OFF) != 0) #define JBE_ISSTRING(je_) (((je_) & JENTRY_TYPEMASK) == JENTRY_ISSTRING) #define JBE_ISNUMERIC(je_) (((je_) & JENTRY_TYPEMASK) == JENTRY_ISNUMERIC) #define JBE_ISCONTAINER(je_) (((je_) & JENTRY_TYPEMASK) == JENTRY_ISCONTAINER) #define JBE_ISNULL(je_) (((je_) & JENTRY_TYPEMASK) == JENTRY_ISNULL) #define JBE_ISBOOL_TRUE(je_) (((je_) & JENTRY_TYPEMASK) == JENTRY_ISBOOL_TRUE) #define JBE_ISBOOL_FALSE(je_) (((je_) & JENTRY_TYPEMASK) == JENTRY_ISBOOL_FALSE) #define JBE_ISBOOL(je_) (JBE_ISBOOL_TRUE(je_) || JBE_ISBOOL_FALSE(je_)) /* Macro for advancing an offset variable to the next JEntry */ #define JBE_ADVANCE_OFFSET(offset, je) \ do { \ JEntry je_ = (je); \ if (JBE_HAS_OFF(je_)) \ (offset) = JBE_OFFLENFLD(je_); \ else \ (offset) += JBE_OFFLENFLD(je_); \ } while(0) /* * We store an offset, not a length, every JB_OFFSET_STRIDE children. * Caution: this macro should only be referenced when creating a JSONB * value. When examining an existing value, pay attention to the HAS_OFF * bits instead. This allows changes in the offset-placement heuristic * without breaking on-disk compatibility. */ #define JB_OFFSET_STRIDE 32 /* * A jsonb array or object node, within a Jsonb Datum. * * An array has one child for each element, stored in array order. * * An object has two children for each key/value pair. The keys all appear * first, in key sort order; then the values appear, in an order matching the * key order. This arrangement keeps the keys compact in memory, making a * search for a particular key more cache-friendly. */ typedef struct JsonbContainer { uint32 header; /* number of elements or key/value pairs, and * flags */ JEntry children[FLEXIBLE_ARRAY_MEMBER]; /* the data for each child node follows. */ } JsonbContainer; /* flags for the header-field in JsonbContainer */ #define JB_CMASK 0x0FFFFFFF /* mask for count field */ #define JB_FSCALAR 0x10000000 /* flag bits */ #define JB_FOBJECT 0x20000000 #define JB_FARRAY 0x40000000 /* convenience macros for accessing a JsonbContainer struct */ #define JsonContainerSize(jc) ((jc)->header & JB_CMASK) #define JsonContainerIsScalar(jc) (((jc)->header & JB_FSCALAR) != 0) #define JsonContainerIsObject(jc) (((jc)->header & JB_FOBJECT) != 0) #define JsonContainerIsArray(jc) (((jc)->header & JB_FARRAY) != 0) /* The top-level on-disk format for a jsonb datum. */ typedef struct { int32 vl_len_; /* varlena header (do not touch directly!) */ JsonbContainer root; } Jsonb; /* convenience macros for accessing the root container in a Jsonb datum */ #define JB_ROOT_COUNT(jbp_) (*(uint32 *) VARDATA(jbp_) & JB_CMASK) #define JB_ROOT_IS_SCALAR(jbp_) ((*(uint32 *) VARDATA(jbp_) & JB_FSCALAR) != 0) #define JB_ROOT_IS_OBJECT(jbp_) ((*(uint32 *) VARDATA(jbp_) & JB_FOBJECT) != 0) #define JB_ROOT_IS_ARRAY(jbp_) ((*(uint32 *) VARDATA(jbp_) & JB_FARRAY) != 0) enum jbvType { /* Scalar types */ jbvNull = 0x0, jbvString, jbvNumeric, jbvBool, /* Composite types */ jbvArray = 0x10, jbvObject, /* Binary (i.e. struct Jsonb) jbvArray/jbvObject */ jbvBinary, /* * Virtual types. * * These types are used only for in-memory JSON processing and serialized * into JSON strings when outputted to json/jsonb. */ jbvDatetime = 0x20, }; /* * JsonbValue: In-memory representation of Jsonb. This is a convenient * deserialized representation, that can easily support using the "val" * union across underlying types during manipulation. The Jsonb on-disk * representation has various alignment considerations. */ struct JsonbValue { enum jbvType type; /* Influences sort order */ union { Numeric numeric; bool boolean; struct { int len; char *val; /* Not necessarily null-terminated */ } string; /* String primitive type */ struct { int nElems; JsonbValue *elems; bool rawScalar; /* Top-level "raw scalar" array? */ } array; /* Array container type */ struct { int nPairs; /* 1 pair, 2 elements */ JsonbPair *pairs; } object; /* Associative container type */ struct { int len; JsonbContainer *data; } binary; /* Array or object, in on-disk format */ struct { Datum value; Oid typid; int32 typmod; int tz; /* Numeric time zone, in seconds, for * TimestampTz data type */ } datetime; } val; }; #define IsAJsonbScalar(jsonbval) (((jsonbval)->type >= jbvNull && \ (jsonbval)->type <= jbvBool) || \ (jsonbval)->type == jbvDatetime) /* * Key/value pair within an Object. * * This struct type is only used briefly while constructing a Jsonb; it is * *not* the on-disk representation. * * Pairs with duplicate keys are de-duplicated. We store the originally * observed pair ordering for the purpose of removing duplicates in a * well-defined way (which is "last observed wins"). */ struct JsonbPair { JsonbValue key; /* Must be a jbvString */ JsonbValue value; /* May be of any type */ uint32 order; /* Pair's index in original sequence */ }; /* Conversion state used when parsing Jsonb from text, or for type coercion */ typedef struct JsonbParseState { JsonbValue contVal; Size size; struct JsonbParseState *next; } JsonbParseState; /* * JsonbIterator holds details of the type for each iteration. It also stores a * Jsonb varlena buffer, which can be directly accessed in some contexts. */ typedef enum { JBI_ARRAY_START, JBI_ARRAY_ELEM, JBI_OBJECT_START, JBI_OBJECT_KEY, JBI_OBJECT_VALUE } JsonbIterState; typedef struct JsonbIterator { /* Container being iterated */ JsonbContainer *container; uint32 nElems; /* Number of elements in children array (will * be nPairs for objects) */ bool isScalar; /* Pseudo-array scalar value? */ JEntry *children; /* JEntrys for child nodes */ /* Data proper. This points to the beginning of the variable-length data */ char *dataProper; /* Current item in buffer (up to nElems) */ int curIndex; /* Data offset corresponding to current item */ uint32 curDataOffset; /* * If the container is an object, we want to return keys and values * alternately; so curDataOffset points to the current key, and * curValueOffset points to the current value. */ uint32 curValueOffset; /* Private state */ JsonbIterState state; struct JsonbIterator *parent; } JsonbIterator; /* Support functions */ extern uint32 getJsonbOffset(const JsonbContainer *jc, int index); extern uint32 getJsonbLength(const JsonbContainer *jc, int index); extern int compareJsonbContainers(JsonbContainer *a, JsonbContainer *b); extern JsonbValue *findJsonbValueFromContainer(JsonbContainer *sheader, uint32 flags, JsonbValue *key); extern JsonbValue *getKeyJsonValueFromContainer(JsonbContainer *container, const char *keyVal, int keyLen, JsonbValue *res); extern JsonbValue *getIthJsonbValueFromContainer(JsonbContainer *sheader, uint32 i); extern JsonbValue *pushJsonbValue(JsonbParseState **pstate, JsonbIteratorToken seq, JsonbValue *jbval); extern JsonbIterator *JsonbIteratorInit(JsonbContainer *container); extern JsonbIteratorToken JsonbIteratorNext(JsonbIterator **it, JsonbValue *val, bool skipNested); extern void JsonbToJsonbValue(Jsonb *jsonb, JsonbValue *val); extern Jsonb *JsonbValueToJsonb(JsonbValue *val); extern bool JsonbDeepContains(JsonbIterator **val, JsonbIterator **mContained); extern void JsonbHashScalarValue(const JsonbValue *scalarVal, uint32 *hash); extern void JsonbHashScalarValueExtended(const JsonbValue *scalarVal, uint64 *hash, uint64 seed); /* jsonb.c support functions */ extern char *JsonbToCString(StringInfo out, JsonbContainer *in, int estimated_len); extern char *JsonbToCStringIndent(StringInfo out, JsonbContainer *in, int estimated_len); extern bool JsonbExtractScalar(JsonbContainer *jbc, JsonbValue *res); extern const char *JsonbTypeName(JsonbValue *jb); extern Datum jsonb_set_element(Jsonb *jb, Datum *path, int path_len, JsonbValue *newval); extern Datum jsonb_get_element(Jsonb *jb, Datum *path, int npath, bool *isnull, bool as_text); #endif /* __JSONB_H__ */