How to retrieve all documents in couchdb database without causing out of memory - couchdb

Question

I have a coucdb database which contains about 200000 tweets, keys are tweet ID. I have a query which needs to retrieve all documents to look for some information. I'm using lightcouch to work with couchdb in a java web app. If I create a dbClient like this:
List<JsonObject>tweets = dbClient.view("_all_docs").query(JsonObject.class);
and then loop through tweets, for each JsonObject in tweets, use
JsonObject tweetJson = dbClient.find(JsonObject.class, tweet.get("id").toString().replaceAll("\"", ""));
to retrieve each tweet one by one it took extremely long time for 200000 documents. If I load all documents in one single query using includeDocs(true)
List<JsonObject>allTweets = dbClient.view("_all_docs").includeDocs(true).query(JsonObject.class);
it caused outofmemory exception since the number of documents are too large. So how can i deal with this problem? I'm thinking about using limit(5000) to retrieve 5000 documents for each time and loop through whole database, but I don't know how to write the loop to continue to retrieve the next 5000 after the first 5000 docs. One possible solution is using startKey and endKey but I'm confused how to use them when the key is tweet ID.

Answer 1

Use queryPage but make sure to use a String as the Key
See: https://github.com/lightcouch/LightCouch/issues/26#event-122327174
0.1.6 still seems to show this behaviour.
A workaround that I found for this goes something like this:
changes = DbClient.changes()
.since(null) // or... since(since) if you want an offset
.includeDocs(true);
int size = 1;
getCursor("0");
while (size > 0 ) {
ChangesResult resultSet = changes.limit(40000).getChanges();
List<ChangesResult.Row> rowList = resultSet.getResults();
for (ChangesResult.Row feed: rowList) {
<instantiate your object via gson>
.
.
.
}
getCursor(resultSet.getLastSeq());
size = rowList.size();
}