database/sqlite
1
0
Fork 0
mirror of https://github.com/sqlite/sqlite.git synced 2025-11-09 14:21:03 +03:00
Code Activity

Describe the JSONB encoding in a header comment to the json.c source file.

Browse Source 
FossilOrigin-Name: 1c0cba3461d6111b3aeb77726880221f1240355f0b57e060febbdeb12fb688c0
This commit is contained in:
drh
2023-09-29 11:17:43 +00:00
parent 8cdab14286
commit ecce6022d5
3 changed files with 106 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
manifest
View File

@@ -1,5 +1,5 @@
C Fix\ssome\sminor\smemory\sissues\sso\sthat\sall\slegacy\stests\snow\spass.
D 2023-09-28T19:11:36.692
C Describe\sthe\sJSONB\sencoding\sin\sa\sheader\scomment\sto\sthe\sjson.c\ssource\sfile.
D 2023-09-29T11:17:43.227
F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -670,7 +670,7 @@ F src/hash.h 3340ab6e1d13e725571d7cee6d3e3135f0779a7d8e76a9ce0a85971fa3953c51
F src/hwtime.h f9c2dfb84dce7acf95ce6d289e46f5f9d3d1afd328e53da8f8e9008e3b3caae6
F src/in-operator.md 10cd8f4bcd225a32518407c2fb2484089112fd71
F src/insert.c 3f0a94082d978bbdd33c38fefea15346c6c6bffb70bc645a71dc0f1f87dd3276
F src/json.c 6ecde7714aed5238881b936edc3f9bf85c2ece02f2b1a41e10f5d5f3e8f89513
F src/json.c 6d2643118360760d589829d5a10d612a0270729ce11b303553502eae70c8f899
F src/legacy.c d7874bc885906868cd51e6c2156698f2754f02d9eee1bae2d687323c3ca8e5aa
F src/loadext.c 98cfba10989b3da6f1807ad42444017742db7f100a54f1032af7a8b1295912c0
F src/main.c 618aeb399e993cf561864f4b0cf6a331ee4f355cf663635f8d9da3193a46aa40
@@ -2123,8 +2123,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
P 2f49687371ada65fef374336c28b352c48ab98dc31282ac82397035efe04ba11
R 3d149364fb767414041d170ea764743b
P 1744bfc669346ff221f28d45fd978863e876a2d2f0b82bcf0e5ee6f0326900cc
R 88ae9ef60dd50edd212e3ca11b3078d3
U drh
Z 6ffc9f7e51690a482c053773cfbc0f4b
Z 174eaa9aa981071dd243f3ac21aacaae
# Remove this line to create a well-formed Fossil manifest.

2
manifest.uuid
View File

@@ -1 +1 @@
1744bfc669346ff221f28d45fd978863e876a2d2f0b82bcf0e5ee6f0326900cc
1c0cba3461d6111b3aeb77726880221f1240355f0b57e060febbdeb12fb688c0

104
src/json.c
View File

@@ -15,11 +15,105 @@
** This file began as an extension in ext/misc/json1.c in 2015. That
** extension proved so useful that it has now been moved into the core.
**
** For the time being, all JSON is stored as pure text. (We might add
** a JSONB type in the future which stores a binary encoding of JSON in
** a BLOB, but there is no support for JSONB in the current implementation.
** This implementation parses JSON text at 250 MB/s, so it is hard to see
** how JSONB might improve on that.)
** The original design stored all JSON as pure text, canonical RFC-8259.
** Support for JSON-5 extensions was added with version 3.42.0 (2023-05-16).
** All generated JSON text still conforms strictly to RFC-8259, but text
** with JSON-5 extensions is accepted as input.
**
** Beginning with version 3.44.0 (pending), these routines also accept
** BLOB values that have JSON encoded using a binary representation we
** call JSONB. The name JSONB comes from PostgreSQL, however the on-disk
** format SQLite JSONB is completely different and incompatible with
** PostgreSQL JSONB.
**
** Decoding and interpreting JSONB is still O(N) where N is the size of
** the input, the same as text JSON. However, the constant of proportionality
** for JSONB is much smaller due to faster parsing. The size of each
** element in JSONB is encoded in its header, so there is no need to search
** for delimiters using persnickety syntax rules. JSONB seems to be about
** 3x faster than text JSON as a result. JSONB is also tends to be slightly
** smaller than text JSON, by 5% or 10%, but there are corner cases where
** JSONB can be slightly larger. Roughtly speaking, though, a JSONB blob
** and the equivalent RFC-8259 text string take up the same amount of space
** on disk.
**
**
** THE JSONB ENCODING:
**
** Every JSON element is encoded in JSONB as a header and a payload.
** The header is between 1 and 9 bytes in size. The payload is zero
** or more bytes.
**
** The lower 4 bits of the first byte of the header determines the
** element type:
**
** 0: NULL
** 1: TRUE
** 2: FALSE
** 3: INT -- RFC-8259 integer literal
** 4: INT5 -- JSON5 integer literal
** 5: FLOAT -- RFC-8259 floating point literal
** 6: FLOAT5 -- JSON5 floating point literal
** 7: TEXT -- Text literal acceptable to both SQL and JSON
** 8: TEXTJ -- Text literal with RFC-8259 escape codes
** 9: TEXT5 -- Text literal with JSON5 and RFC-8259 escapes
** 10: TEXTRAW -- Text literal with unescaped ', ", or \ characters
** 11: ARRAY
** 12: OBJECT
**
** The other three possible values (13-15) are reserved for future
** enhancements.
**
** The upper 4 bits of the first byte determine the size of the header
** and sometimes also the size of the payload. If X is the first byte
** of the element and if X>>4 is between 0 and 11, then the payload
** will be that many bytes in size and the header is exactly one byte
** in size. Other four values for X>>4 (12-15) indicate that the header
** is more than one byte in size and that the payload size is determined
** by the remainder of the header, interpreted as a unsigned big-endian
** integer.
**
** Value of X>>4 Size integer Total header size
** ------------- -------------------- -----------------
** 12 1 byte (0-255) 2
** 13 2 byte (0-65535) 3
** 14 4 byte (0-4294967295) 5
** 15 8 byte (0-1.8e19) 9
**
** The payload size need not be expressed in its minimal form. For example,
** if the payload size is 10, the size can be expressed in any of 5 different
** ways: (1) (X>>4)==10, (2) (X>>4)==12 following by on 0x0a byte,
** (3) (X>>4)==13 followed by 0x00 and 0x0a, (4) (X>>4)==14 followed by
** 0x00 0x00 0x00 0x0a, or (5) (X>>4)==15 followed by 7 bytes of 0x00 and
** a single byte of 0x0a. The shorter forms are preferred, of course, but
** sometimes when generating JSONB, the payload size is not known in advance
** and it is convenient to reserve sufficient header space to cover the
** largest possible payload size and then come back later and patch up
** the size when it becomes known, resulting in a non-minimal encoding.
**
** The value (X>>4)==15 is not actually used in the current implementation
** (as SQLite is currently unable handle BLOBs larger than about 2GB)
** but is included in the design to allow for future enhancements.
**
** The payload follows the header. NULL, TRUE, and FALSE have no payload and
** their payload size must always be zero. The payload for INT, INT5,
** FLOAT, FLOAT5, TEXT, TEXTJ, TEXT5, and TEXTROW is text. Note that the
** "..." or '...' delimiters are omitted from the various text encodings.
** The payload for ARRAY and OBJECT is a list of additional elements that
** are the content for the array or object. The payload for an OBJECT
** must be an even number of elements. The first element of each pair is
** the label and must be of type TEXT, TEXTJ, TEXT5, or TEXTRAW.
**
** A valid JSONB blob consists of a single element, as described above.
** Usually this will be an ARRAY or OBJECT element which has many more
** elements as its content. But the overall blob is just a single element.
**
** Input validation for JSONB blobs simply checks that the element type
** code is between 0 and 12 and that the total size of the element
** (header plus payload) is the same as the size of the BLOB. If those
** checks are true, the BLOB is assumed to be JSONB and processing continues.
** Errors are only raised if some other miscoding is discovered during
** processing.
*/
#ifndef SQLITE_OMIT_JSON
#include "sqliteInt.h"