PgConf.Russia 2017

I love complex knowledge domains, strong typing in applications, and 3NF, but I hate ORM. That is why I’ve been actively storing serialized structures in JSON fields (even before the JSON type was introduced). In this talk, I will tell you about some specifics of storing complex structures within DBMS fields, what problems can arise, and how to cushion the blow.

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Currently, to execute SQL queries PostgreSQL uses interpreter, which implements Volcano-style iteration model. At the same time it’s possible to get significant speedup by dynamically JIT-compiling query “on-the-fly”. In this case it’s possible to generate code that is specialized for given SQL query, and perform compiler optimizations using the information about table structure and data types that is already known at run time. This approach is especially important for complex queries, which performance is CPU-bound.

The new ISO/IEC 9075-2:2016 standard specifies JSON data and operations syntax and semantics specifics for SQL. This talk overviews the requirements of this standard, and focuses on the differences between them and the actual implementation of JSON/JSONB in PostgreSQL. Special attention will be paid to JSON Path (XPath analogue), SQL/JSON functions and our plans to make Postgres compliant with this standard.

VIDEO