How long would it take me to complete Bitcoin client upgrade?

[aarreeaa]

I currently run bitcoin v0.8.6-beta on this PC and received note that it is obsolete.

Last time that I installed bitcoin wallet software, I think that it re indexed all blocks and that took 3 or 4 days.

I would like to know, if I install newest version (bitcoin-0.10.2), will it again need to re index all blocks?

[gmaxwell]

it should not if your chain is not corrupted and you shut it down cleanly first. The databases are forward compatible.

If a reindex is taking 3 or 4 days your computer is very slow or there is something wrong with it. On a several year old desktop (3.2GHz quad core with SSD) I can download and fully sync in about 3 _hours_ with the current software; and reindexing is somewhat faster.

[aarreeaa]

Recently my laptop (1.9GHz dual core) took ~5 hours to synchronize ~3 weeks of blocks.

My PC is 3.1 GHz dual core and it synchronizes 1 day worth of blocks within 10-20 minutes.