In-Memory Databases

How expensive would it be to have all of your production data in an in-memory database as opposed to slow-ass SSD or HDD ones? Or can you do some sort of caching where it puts certain parts in RAM but not all of it? How would that work?

I only have basic experience working with SQLite and MongoDB, but the ideas of super-fast IMDBs is appealing. I've vaguely heard of redis, but I don't know how you'd use it.

Or can you do some sort of caching where it puts certain parts in RAM but not all of it?

Isn't that pretty much the reason databases are even worth bothering with? I thought it's pretty much just a ``general purpose'' datastructure with good caching.

Check the size of your database, then look up how much that amount of RAM costs. That's how expensive it will be.

>>3
But what ratio of RAM:SSD should you have?

>>4
For in-memory the ratio will be around 1:0.

OrigoDB might be what you are looking for

you see ivan, when you put database in RAM you have 100% uptime for fear of losing data

>>7
it'd obviously back up to persistent storage every now and then, but for performance reasons, it would mostly be in RAM

Prolog/Datalog

You can build a 1TB RAM server for 15k$
PCPartPicker part list: https://pcpartpicker.com/list/fkjKhy
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CPU: Intel - Xeon E5-2603 V3 1.6GHz 6-Core OEM/Tray Processor ($208.32 @ Amazon)
CPU: Intel - Xeon E5-2603 V3 1.6GHz 6-Core OEM/Tray Processor ($208.32 @ Amazon)
CPU Cooler: Noctua - NH-U12DXi4 55.0 CFM CPU Cooler ($64.17 @ Newegg Business)
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Motherboard: Supermicro - MBD-X10DRI-O EATX Dual-CPU LGA2011-3 Narrow Motherboard ($351.98 @ Newegg)
Memory: Crucial - 64GB (1 x 64GB) Registered DDR4-2400 Memory ($819.00 @ B&H)
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Memory: Crucial - 64GB (1 x 64GB) Registered DDR4-2400 Memory ($819.00 @ B&H)
Memory: Crucial - 64GB (1 x 64GB) Registered DDR4-2400 Memory ($819.00 @ B&H)
Memory: Crucial - 64GB (1 x 64GB) Registered DDR4-2400 Memory ($819.00 @ B&H)
Memory: Crucial - 64GB (1 x 64GB) Registered DDR4-2400 Memory ($819.00 @ B&H)
Memory: Crucial - 64GB (1 x 64GB) Registered DDR4-2400 Memory ($819.00 @ B&H)
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Memory: Crucial - 64GB (1 x 64GB) Registered DDR4-2400 Memory ($819.00 @ B&H)
Memory: Crucial - 64GB (1 x 64GB) Registered DDR4-2400 Memory ($819.00 @ B&H)
Memory: Crucial - 64GB (1 x 64GB) Registered DDR4-2400 Memory ($819.00 @ B&H)
Memory: Crucial - 64GB (1 x 64GB) Registered DDR4-2400 Memory ($819.00 @ B&H)
Memory: Crucial - 64GB (1 x 64GB) Registered DDR4-2400 Memory ($819.00 @ B&H)
Memory: Crucial - 64GB (1 x 64GB) Registered DDR4-2400 Memory ($819.00 @ B&H)
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Storage: Micron - 1100 2TB 2.5" Solid State Drive ($297.00 @ Amazon)
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Generated by PCPartPicker 2018-07-08 10:06 EDT-0400

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Price breakdown by merchant:
https://pcpartpicker.com/list/pZFyxG/by_merchant/

CPU: Intel - Xeon E5-2650 2GHz 8-Core Processor ($103.89 @ Newegg Marketplace)
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Memory: Mushkin - Proline 32GB (1 x 32GB) Registered DDR3-1066 Memory ($249.89 @ OutletPC)
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Video Card: PowerColor - Radeon RX 560 - 896 4GB Video Card ($109.99 @ Newegg)
Case: Phanteks - Enthoo Pro ATX Full Tower Case ($79.99 @ Newegg)
Power Supply: EVGA - SuperNOVA G2 1300W 80+ Gold Certified Fully-Modular ATX Power Supply ($179.99 @ B&H)
Total: $5095.95
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-07-08 10:12 EDT-0400

or 4 servers with 256GB ram and cost of 2K$
PCPartPicker part list: https://pcpartpicker.com/list/3kgNyX
Price breakdown by merchant: https://pcpartpicker.com/list/3kgNyX/by_merchant/

CPU: Intel - Xeon E5-2609 2.4GHz Quad-Core Processor ($65.00 @ Newegg Marketplace)
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Storage: Team - L5 LITE 3D 480GB 2.5" Solid State Drive ($79.99 @ Newegg)
Video Card: PowerColor - Radeon RX 560 - 896 4GB Video Card ($109.99 @ Newegg)
Case: Phanteks - Enthoo Pro ATX Full Tower Case ($79.99 @ Newegg)
Power Supply: EVGA - SuperNOVA G3 750W 80+ Gold Certified Fully-Modular ATX Power Supply ($59.99 @ B&H)
Total: $2063.77
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-07-08 10:18 EDT-0400

Whatever happened to RAM drives?

>>13

mount -t tmpfs -o size=1024g tmpfs /mnt/ramdisk

>>14
That's the opposite of what I mean.
You're talking about turning RAM into a hard drive.

I mean a PCIe card that lets you install additional RAM in your computer (more than what fits in the DIMM slots). Then you can use it as a RAM drive.

Let's say your motherboard only supports 64GB of RAM, but you actually want way more. But you don't want to buy a super expensive enterprise server board that will cost thousands of bucks. But your consumer grade (cheap/affordable) motherboard has some unused expansion slots. So you get some more RAM and some RAM drive cards to put in the expansion slots. At least that's how it's supposed to be, anyway. The last time I heard of a RAM drive was years ago, for like DDR2 or DDR3 or something. Really old stuff.

>>15
Well then, to answer your original question: Flash memory prices killed those off.

>>16
SSDs are fast, but still not RAM fast.

>>15,17
You can have 2-3 M.2 drives that are 5-6 times faster than SATA or buy an expensive PCIE SSD that provide top speed.
PCIE SSD are the todays ram drive.