Hi Hackers,
== Background ==
While reviewing a patch, I noticed that quoteOneName() duplicates the logic of quote_identifier() for adding double quotes to identifiers. The main difference is that quoteOneName() does *not* honor the GUC `quote_all_identifiers`.
The typical usage pattern of quoteOneName() looks like this:
```
// Define a local buffer with size MAX_QUOTED_NAME_LEN
// MAX_QUOTED_NAME_LEN = MAX_NAMELEN * 2 + 3 to ensure no overflow
char attname[MAX_QUOTED_NAME_LEN];
// Add quotes and copy into the stack buffer
quoteOneName(attname, RIAttName(pk_rel, riinfo->pk_attnums[riinfo->nkeys - 1]));
// Copy the quoted identifier into a StringInfo
appendStringInfoString(&querybuf, attname);
```
This pattern is expensive because:
* it allocates a larger-than-necessary buffer on the stack
* it incurs two pallocs and two data copies
Looking further, the common pattern around quote_identifier() is similar:
```
appendStringInfoString(&relations, quote_identifier(relname));
```
This also incurs two pallocs and two copies: quote_identifier() allocates a temporary buffer and copies the quoted identifier into it, and then appendStringInfoString() may allocate and copy again.
== Idea ==
I'd like to propose introducing `appendStringInfoIdentifier()`, which adds the quoting logic directly to StringInfo. The goals are:
* eventually deprecate quoteOneName() — I'm not aware of a reason why it should ignore the GUC `quote_all_identifiers`
* simplify the usage patterns for quoting identifiers
* avoid unnecessary intermediate buffers, pallocs, and data copies
== About the attached patch ==
Attached v1 is not intended to be the final version — it is mainly to demonstrate the idea and get feedback on the design direction.
* 0001 implements `appendStringInfoIdentifier()` and uses it in a few places
* 0002 switches ri_triggers.c to use it, resolving a complicated usage pattern and showing a path toward removing quoteOneName()
Comments and suggestions on the overall direction would be very welcome.
