If I correctly understand your question, you would want to create a table in the database for each of your existing text files. To suck the entire contents out of a table, you would run a query against it (most likely SELECT * FROM tablename;, if you really do want everything) and use the query object's fetchrow_array method in list context.

However, if you do that, the performance improvement isn't likely to be much on reads or appends, although deleting data from the start of the list would probably improve considerably. Sucking an entire file into memory tends to be faster than sucking an entire database table into memory for the simple reason that it's going through a less complex access mechanism. The major advantages of databases are in seeking data (so you don't have to bring everything into memory) and concurrency, and slurping the whole table doesn't take advantage of either of them.

So, what do you actually do with the data after reading it? Do you really need to have everything in memory or can you use SQL to specify a subset of the data which is actually interesting to you?