Add json-columns module: JSON columns in Hibernate 7.4.14 (@JdbcTypeCode(SqlTypes.JSON)), JSONB querying, GIN/expression indexes, dirty checking, Jackson 3 vs 2 on PostgreSQL 18.6 and MySQL 8.0.46

Co-Authored-By: Claude Sonnet 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_017ic4b6Kg9RWSTJzyz6KP9X
2026-10-30 17:00:46 +00:00
parent 98f4ed7411
commit b83cc9988e
51 changed files with 3178 additions and 0 deletions
@@ -0,0 +1,44 @@
+
+== baseline: persist a Product whose Map holds only JSON-native Java types (String, Integer, Double, Map, List)
+sql> insert into product (attributes,dimensions,name,specs,tags) values (?,?,?,?,?)
+
+== load, change nothing, commit
+UPDATE statements: 0
+
+== in-place mutations: load, mutate the object graph, commit, count UPDATEs
+attributes.put("color", "blue")                                      -> 1 UPDATE
+      update product set attributes=?,dimensions=?,name=?,specs=?,tags=? where id=?
+attributes.remove("stock")                                           -> 1 UPDATE
+      update product set attributes=?,dimensions=?,name=?,specs=?,tags=? where id=?
+((Map) attributes.get("nested")).put("k2", 1)  [nested map]          -> 1 UPDATE
+      update product set attributes=?,dimensions=?,name=?,specs=?,tags=? where id=?
+((List) nested.get("k")).add(4)  [list inside map]                   -> 1 UPDATE
+      update product set attributes=?,dimensions=?,name=?,specs=?,tags=? where id=?
+tags.add("c")                                                        -> 1 UPDATE
+      update product set attributes=?,dimensions=?,name=?,specs=?,tags=? where id=?
+specs.setMaterial("brass")  [POJO setter]                            -> 1 UPDATE
+      update product set attributes=?,dimensions=?,name=?,specs=?,tags=? where id=?
+specs.getCertifications().add("UL")  [list inside POJO]              -> 1 UPDATE
+      update product set attributes=?,dimensions=?,name=?,specs=?,tags=? where id=?
+setDimensions(new Dimensions(9,9,9))  [record replaced]              -> 1 UPDATE
+      update product set attributes=?,dimensions=?,name=?,specs=?,tags=? where id=?
+setDimensions(equal record)  [no real change]                        -> 0 UPDATE
+
+== the changes really reached the database
+attributes = {"color": "blue", "price": 19.9, "nested": {"k": [1, 2, 3, 4], "k2": 1}}
+tags       = ["a", "b", "c"]
+specs      = {"material": "brass", "weightKg": 1.8, "certifications": ["CE", "UL"]}
+
+== spurious UPDATEs: nothing changed, Hibernate writes anyway
+persist() with attributes.price = new BigDecimal("19.90") -> 1 UPDATE right after the INSERT
+   sql> insert into product (attributes,dimensions,name,specs,tags) values (?,?,?,?,?)
+   sql> update product set attributes=?,dimensions=?,name=?,specs=?,tags=? where id=?
+stored price after that persist: 19.90
+then a plain load + commit of that row -> 0 UPDATE
+load + commit of a row whose POJO has NO equals(), nothing touched -> 1 UPDATE
+   sql> select l1_0.id,l1_0.specs from loose l1_0 where l1_0.id=?
+   sql> update loose set specs=? where id=?
+same for Specs, which HAS equals() (Product row, nothing touched) -> 0 UPDATE
+
+== @DynamicUpdate: only the changed JSON column is written
+sql> update dyn set a=? where id=?