Make PostgreSQL ready for Gramps 6.0

[DavidMStraub]

I have not tested this yet. Will leave as draft until it's ready to merge.

[dsblank]

Does postgresql have this convention:

Suggested change

	"WHERE table_name = %s AND column_name = %s",
	"WHERE table_name = ? AND column_name = ?",

[DavidMStraub]

Yes, that's what psycopg2 uses - it's like that in the rest of the addon as well.

[DavidMStraub]

By the way - since TEXT is hard-coded in DBAPI, we cannot use native JSON types, correct?

[dsblank]

By the way - since TEXT is hard-coded in DBAPI, we cannot use native JSON types, correct?

One of the many aspects we learn as we port to different engines 😄

In order for Postgresql to use a different type, we'll have to have an abstraction for that in the base class. Like:

class DBAPI():
    json_data_field_type = "TEXT

and use that when we create the fields. There may be a couple of other abstractions if we have a generic SQL query method. I'll make a PR for the json_data_field_type in the base DBAPI class.

[dsblank]

I may have misunderstood your question: I think Postgresql can use whatever type you want, as long as it acts like a string in Python.

[DavidMStraub]

Actually, after reading up a bit, I realize I was making a wrong assumption - I thought the JSON type was more performant or offered more possibilities to query it, but it turns out it doesn't do much compared to TEXT, only enforcing JSON syntax, which we don't really need. So, nothing to do right now ☺️

It will get more interesting/complicated if/when we start to query into the JSON structure itself, where each engine has their own syntax; like I had to do for the Sifts search library used in Gramps Web, e.g.

https://github.com/DavidMStraub/sifts/blob/main/src/sifts/core.py#L428
vs
https://github.com/DavidMStraub/sifts/blob/main/src/sifts/core.py#L573

[dsblank]

It will get more interesting/complicated if/when we start to query into the JSON structure itself

That is on the schedule for 6.1 (soon!). We should coordinate now to make sure that whatever we do, that it works across at least postgresql and sqlite.

Can you test this query in postgresql on new database structure:

SELECT json_extract(json_data, '$.primary_name.surname_list[0].surname') 
FROM person 
WHERE (json_extract(json_data, '$.gender') = 0) 
ORDER BY json_extract(json_data, '$.handle') DESC, json_extract(json_data, '$.gender');

That will be a good start. We'll have to check operators, but there is a test suite that I'll port to whatever approach we take.

[DavidMStraub]

Sorry, but I have no capacity to check these things before the 6.0 release. Can we please not start new breaking database backend changes before 6.0 is fully released?

[DavidMStraub]

drop_column still needs to be added