\c 25 200i

/ c: count | ht: historical table | st: snapshot table | rt: realtime table | tx: transaction
generateRandomHdbFrom:{[c;u]flip`e`v`t!(c?c*4;u@c?count u;1+til c)}
generateRandomHdb:generateRandomHdbFrom[;"abcdefghijklmnopqrstuvwxyz"]
appendToHdbFrom:{[ht;c;u]ht upsert flip(c?100000*count u;c?u;(1+$[0~count lastTx:select [-1] t from ht;0;first lastTx@`t]))}
appendToHdb:appendToHdbFrom[;;"abcdefghijklmnopqrstuvwxyz"]

createSnapshotTable:{[ht;tx]tx:$[-1~tx;0Wj;tx];s:`v xasc select e,v from ht where t <= tx;w:last each value group s@`e;`e xkey s@w}

/ input:    1   2  3  4  5  6  7  8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
/ output: 676 169 81 49 36 25 16 16 9  9  9  9  4  4  4  4  4  4  4  4  4  4  4  4  4  1
generateRandomTableHandles:{[crossProductAlphabetSize]`$(":db/",/:raze T,\:/:T:cut[crossProductAlphabetSize;"abcdefghijklmnopqrstuvwxyz"]),'"/"}

resetHdbTables:{[th]set[;([] e:`long$(); v:`char$(); t:`long$())] each th}

resetHdb:{}

/ RUN
/ appendToTable[;1000000] each th
/ appendToTable[;10] each th

/ RESULTS in MBP with 16 GB, 2.6 GHz Intel Core i7 and SSD:

/ 169 Tables
/ 169 million rows appended in 22 seg. total ~2.87 GB (169 tables, 1 million each)
/ after that, 10 rows are appended to all 169 tables in 50-200 ms

/ 25 Tables
/ 25 million rows appended in 3.7 seg. total ~425MB (25 tables, 1 million each)
/ after that, 10 rows are appended to all 25 tables in ~25ms

/ 9 Tables
/ 9 million rows appended in 1.5 seg. total ~153MB (9 tables, 1 million each)
/ after that, 10 rows are appended to all 9 tables in ~8ms

/ 4 Tables
/ 4 million rows appended in 0.6 seg. total ~68MB (4 tables, 1 million each)
/ after that, 10 rows are appended to all 4 tables in ~4ms

/ Throughput : 10-250 writes per second w/o transaction log