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cdsc_reddit/datasets/add_new_month.sh
Benjamin Mako Hill 8965a251b6 refactor datasets/ pipeline; add build/add-month workflows
Replace the four per-type scripts (comments/submissions x part1/part2)
with two merged scripts that share all of their plumbing — only the
schema and JSON parser differ between types. Drop the per-source part
rolling; one parquet per input zst, since Spark handles big parquet
files via internal row groups.

Add two thin runner scripts for the two common workflows:
build_from_scratch.sh wipes the temp dirs and processes everything,
add_new_month.sh takes YYYY-MM and parses just that month before
re-running the Spark sort. Every step in the runners is a separate
command so individual stages can be copied out and run standalone
for debugging.

Also fixes several lurking bugs in the original code: the hardcoded
/gscratch/comdata/users/nathante/ output path in comments Part 2;
the df2 = df.sortWithinPartitions typo in submissions Part 2 that
threw away the preceding global sort; references to a missing
parse_submissions.sh in the old .sh runners; and the asymmetry where
comments_2_parquet_part1.py wasn't per-file/fire-driven the way
submissions_2_parquet_part1.py was.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-05-25 16:30:54 -07:00

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#!/usr/bin/env bash
#
# Add a single new month of dumps to the existing parquet datasets.
#
# Processes only the RC_<month>.zst and RS_<month>.zst files (Part 1),
# leaving the existing per-source temp parquet files untouched, then
# re-runs the Part 2 Spark sort + repartition over the full temp dir so
# the final by_subreddit / by_author datasets pick up the new data.
#
# Usage:
# add_new_month.sh YYYY-MM
#
# Example:
# add_new_month.sh 2025-03
#
# Every command below is independently runnable — to debug, copy a line
# out and run it directly. For a full rebuild instead, see
# build_from_scratch.sh.
#
# Note on cost: Part 2 always re-sorts the full corpus (the sort is global,
# not incremental), so this gets slightly slower each month. For the
# monthly cadence this is fine; if the sort becomes a bottleneck we'd
# need to rearchitect Part 2 to merge-append instead of re-sort.
set -e
cd "$(dirname "$0")"
MONTH="${1:-}"
if [ -z "$MONTH" ]; then
echo "Usage: $0 YYYY-MM" >&2
exit 1
fi
# --- Part 1: parse the new month's dumps (no wipe) -------------------------
# parse the new comments file
python3 parquet_part1.py comments parse_dump "RC_${MONTH}.zst"
# parse the new submissions file
python3 parquet_part1.py submissions parse_dump "RS_${MONTH}.zst"
# --- Part 2: re-sort the full corpus including the new data ---------------
# sort comments and overwrite reddit_comments_by_{subreddit,author}.parquet
start_spark_and_run.sh 1 parquet_part2.py comments
# sort submissions and overwrite reddit_submissions_by_{subreddit,author}.parquet
start_spark_and_run.sh 1 parquet_part2.py submissions