Apr 8, 2026 · Accepted (slight positive trend)

Experiment 021: SQLITE_DEFAULT_PCACHE_INITSZ=128

Date: 2026-04-08

Status: Accepted (slight positive trend)

Hypothesis

Pre-allocating 128 page cache slots per connection at startup (instead of the

default ~20) avoids incremental malloc pressure during the first few queries.

With 2-4 readers + 1 writer, each connection does startup page cache growth

that this flag batches into a single contiguous allocation.

Change

Added compile flag: SQLITE_DEFAULT_PCACHE_INITSZ=128

(Applied on top of experiment 020 — cumulative.)

Results

2 wins, 0 regressions, 15 neutral.

Decision

Accepted — slight positive trend on larger result sets. Zero code complexity,

minimal memory cost (~512KB total across all connections at 4KB pages). The

improvement likely comes from fewer reallocs during page cache warm-up in the

benchmark's per-test Database.open cycle.