https://bugs.openldap.org/show_bug.cgi?id=10428

Issue ID: 10428 Summary: Make larger key sizes available at compile time Product: LMDB Version: unspecified Hardware: All OS: All Status: UNCONFIRMED Keywords: needs_review Severity: normal Priority: --- Component: liblmdb Assignee: bugs@openldap.org Reporter: marlowsd@gmail.com Target Milestone: ---

I discovered that I can increase the key size to 1982 bytes with the following patch

``` *************** *** 1053,1059 **** #define METADATA(p) ((void *)((char *)(p) + PAGEHDRSZ))

/** ITS#7713, change PAGEBASE to handle 65536 byte pages */ ! #define PAGEBASE ((MDB_DEVEL) ? PAGEHDRSZ : 0)

/** Number of nodes on a page */ #define NUMKEYS(p) ((MP_LOWER(p) - (PAGEHDRSZ-PAGEBASE)) >> 1) --- 1054,1061 ---- #define METADATA(p) ((void *)((char *)(p) + PAGEHDRSZ))

/** ITS#7713, change PAGEBASE to handle 65536 byte pages */ ! #define PAGEBASE PAGEHDRSZ ! // #define PAGEBASE ((MDB_DEVEL) ? PAGEHDRSZ : 0)

/** Number of nodes on a page */ #define NUMKEYS(p) ((MP_LOWER(p) - (PAGEHDRSZ-PAGEBASE)) >> 1) ```

and then passing `-DMDB_MAXKEYSIZE=0` at compile time. I didn't want to use `MDB_DEVEL` because this is for a production use case.

Is this feature ready to be widely used? If so, could it be given a compile-time (or run-time) flag please?

Background: this is for Glean (https://github.com/facebookincubator/Glean/pull/663), this page explains our DB structure https://glean.software/docs/implementation/db/.