Transcript

HCC performance and Compression Ratio – Demo

Now, first off, for comparison, I’ll create a table which is not compressed at all. Then I’ll create a table which I’ll actually call CompHCC with the same structure, and for this table, I’ll use compress for archive high. That’s the highest level of hybrid columnar compression that we can do. It’s also of course the slowest and requires the most CPU usage. Just for comparison purposes, I’ll create a third table which uses the older mechanism of deduplication for compression.

Now, let’s just insert a couple of rows. I’ll enable timing so we can see if we do get any performance differences. Now, to get any compression at all, you must use the direct load. I’m deliberately using data that should be amenable to compression and also to deduplication so we can get some sensible comparisons.

How many rows? Well, let’s have, say, a million rows or even 100,000 rows. Now, I’ll copy those rows into my other tables, again being sure to use a direct load, set up the same length of times before and finally into my hybrid columnar compression table. We can see there’s a significant time penalty on this.

Now, I think it’s probably safe to assume that in the majority of cases, the extra delay for inserting into hybrid columnar compression tables – and remember I did choose the highest compression and therefore the worst performance – the delay is probably acceptable because in most environments, the loaded data is going to be in a synchronous or offline operation.

Let us just see how much space is actually being taken up. So first, my not-compressed table, then the deduplicated table and finally my HCC table, and there we see it. So the uncompressed data, 234 blocks; the deduplication, 150, okay; but the hybrid columnar compression table, down to seven. In that ratio, that’s worth about 30 to one. Of course, the data I chose is very amenable to compression, but particularly interesting is the comparison with deduplication because that data is perfect for deduplicating as well.

So we can see that hybrid columnar compression really does work.

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