Apoending rows to a table on disk

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1

Hi, I have looked the pub/sub mechanisim in u.q. I want to know if you upsert 2 rows in a table. How do you put *only* those 2 rows on disk ? Because saving the table using 0: or 1: or the save function will overwrite everything on disk and start from scratch ?

2

/ The functional dot apply takes 4 parameters. The on-disk table is overwritten if you put colon as the third param. The on-disk table is appended if you put comma as the third param.


q)newQuote:(time:(“p”$2016.06.01)+til 3; sym:AB`C; price:0.1*til 3);

q)select from newQuote

time sym price

---------------------------------------

2016.06.01D00:00:00.000000000 A 0

2016.06.01D00:00:00.000000001 B 0.1

2016.06.01D00:00:00.000000002 C 0.2

q).[:/tmp/hdb/quote/; (); :; .Q.en[:/tmp/hdb/; newQuote]];

q)system “l /tmp/hdb”;

q)select from quote

time sym price

---------------------------------------

2016.06.01D00:00:00.000000000 A 0

2016.06.01D00:00:00.000000001 B 0.1

2016.06.01D00:00:00.000000002 C 0.2

q).[:/tmp/hdb/quote/; (); ,; .Q.en[:/tmp/hdb/; newQuote]];

q)system “l /tmp/hdb”;

q)select from quote

time sym price

---------------------------------------

2016.06.01D00:00:00.000000000 A 0

2016.06.01D00:00:00.000000001 B 0.1

2016.06.01D00:00:00.000000002 C 0.2

2016.06.01D00:00:00.000000000 A 0

2016.06.01D00:00:00.000000001 B 0.1

2016.06.01D00:00:00.000000002 C 0.2