From 29940d51eb8b6b220d53940ecbc212cea78159ae Mon Sep 17 00:00:00 2001
From: Terry Truong <terry06890@gmail.com>
Date: Tue, 17 May 2022 10:41:12 +1000
Subject: Improve enwiki description extraction

Adjust enwiki code to handle single dump file, and add scripts for
'convenient' page-content lookup.
---
 backend/data/enwiki/genDumpIndexDb.py | 56 +++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100755 backend/data/enwiki/genDumpIndexDb.py

(limited to 'backend/data/enwiki/genDumpIndexDb.py')

diff --git a/backend/data/enwiki/genDumpIndexDb.py b/backend/data/enwiki/genDumpIndexDb.py
new file mode 100755
index 0000000..13f7eb6
--- /dev/null
+++ b/backend/data/enwiki/genDumpIndexDb.py
@@ -0,0 +1,56 @@
+#!/usr/bin/python3
+
+import sys, os, re
+import bz2
+import sqlite3
+
+usageInfo =  f"usage: {sys.argv[0]}\n"
+usageInfo += "Reads a Wikimedia enwiki dump index file,\n"
+usageInfo += "and stores it's offset and title data to an sqlite db.\n"
+if len(sys.argv) > 1:
+	print(usageInfo, file=sys.stderr)
+	sys.exit(1)
+
+indexFile = "enwiki-20220501-pages-articles-multistream-index.txt.bz2" # 22,034,540 lines
+indexDb = "dumpIndex.db"
+
+# Check for existing db
+if os.path.exists(indexDb):
+	print("ERROR: Existing {}".format(indexDb), file=sys.stderr)
+	sys.exit(1)
+# Create db
+dbCon = sqlite3.connect(indexDb)
+dbCur = dbCon.cursor()
+dbCur.execute("CREATE TABLE offsets (title TEXT PRIMARY KEY, offset INT, next_offset INT)")
+# Reading index file
+lineRegex = re.compile(r"([^:]+):([^:]+):(.*)")
+lastOffset = 0
+lineNum = 0
+titlesToAdd = []
+with bz2.open(indexFile, mode='rt') as file:
+	for line in file:
+		lineNum += 1
+		if lineNum % 1e5 == 0:
+			print("At line {}".format(lineNum))
+		#
+		match = lineRegex.fullmatch(line.rstrip())
+		(offset, _, title) = match.group(1,2,3)
+		offset = int(offset)
+		if offset > lastOffset:
+			for t in titlesToAdd:
+				try:
+					dbCur.execute("INSERT INTO offsets VALUES (?, ?, ?)", (t, lastOffset, offset))
+				except sqlite3.IntegrityError as e:
+					# Accounts for certain entries in the file that have the same title
+					print("Failed on title \"{}\": {}".format(t, e))
+			titlesToAdd = []
+			lastOffset = offset
+		titlesToAdd.append(title)
+for title in titlesToAdd:
+	try:
+		dbCur.execute("INSERT INTO offsets VALUES (?, ?, ?)", (title, lastOffset, -1))
+	except sqlite3.IntegrityError as e:
+		print("Failed on title \"{}\": {}".format(t, e))
+# Close db
+dbCon.commit()
+dbCon.close()
-- 
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