[GitHub] janl opened a new issue #877: Make peruser use the `/` trick to avoid ?too many databases in one directory? issue

[gi...@git.apache.org]

janl opened a new issue #877: Make peruser use the `/` trick to avoid ?too many databases in one directory? issue
URL: https://github.com/apache/couchdb/issues/877
 
 
   When you put a slash (`/`) into a database name, CouchDB will create a sub-directory inside of `database_dir`. This can be used to avoid issues with too many individual .couch files in a single directory (different file systems have different limitations here). This is especially relevant for peruser setups.
   
   couch_peruser creates databases with a prefix (`userdb-`) and the hex representation of the username. I suggest that if that hex representation is longer than two characters, we insert a `/` after the first two. Like so:
   
   `userdb-c4d3ff3` becomes `userdb-c4/d3ff3`
   
   ### Implementation note:
   
   For installations that start on the existing scheme and are upgraded to a CouchDB version with this feature, the couch_peruser model should include fallback code that can handle at least the deletion of old-style databases.
   
   In addition there should be a configuration option to disable the feature for installations that don?t want to migrate to the new system when they update their CouchDB version. There might be external systems that need updating to handle the `/` in URLs (as they need to be encoded as `%2[Ff]` and not all utility scripts might do this properly.
   
   ### Related Work
   Git uses a similar scheme for it?s objects subdirectory:
   
   ```terminal
   > ls .git/objects/
   00	14	28	3c	50	64	78	8c	a0	b4	c8	dc	f0
   01	15	29	3d	51	65	79	8d	a1	b5	c9	dd	f1
   02	16	2a	3e	52	66	7a	8e	a2	b6	ca	de	f2
   03	17	2b	3f	53	67	7b	8f	a3	b7	cb	df	f3
   04	18	2c	40	54	68	7c	90	a4	b8	cc	e0	f4
   05	19	2d	41	55	69	7d	91	a5	b9	cd	e1	f5
   06	1a	2e	42	56	6a	7e	92	a6	ba	ce	e2	f6
   07	1b	2f	43	57	6b	7f	93	a7	bb	cf	e3	f7
   08	1c	30	44	58	6c	80	94	a8	bc	d0	e4	f8
   09	1d	31	45	59	6d	81	95	a9	bd	d1	e5	f9
   0a	1e	32	46	5a	6e	82	96	aa	be	d2	e6	fa
   0b	1f	33	47	5b	6f	83	97	ab	bf	d3	e7	fb
   0c	20	34	48	5c	70	84	98	ac	c0	d4	e8	fc
   0d	21	35	49	5d	71	85	99	ad	c1	d5	e9	fd
   0e	22	36	4a	5e	72	86	9a	ae	c2	d6	ea	fe
   0f	23	37	4b	5f	73	87	9b	af	c3	d7	eb	ff
   10	24	38	4c	60	74	88	9c	b0	c4	d8	ec	info
   11	25	39	4d	61	75	89	9d	b1	c5	d9	ed	pack
   12	26	3a	4e	62	76	8a	9e	b2	c6	da	ee
   13	27	3b	4f	63	77	8b	9f	b3	c7	db	ef
   ```
   
   ```terminal
   > ls .git/objects/00/
   09488cc8dfbaa6471174a2e1d0247ee15ab89a  9a148b4800c773504037a9231d2827b7337623
   1be12127153c2647125767e1b1a23e7aafe44a  a393e01c85b9be4819f0c6dc43d5984fc622a4
   2bcb25013c8bae71192989b941f84b7cde3ce1  c3d56e167a73321ce34e7241b5290cf9252478
   2cb4d33b40520d7f19d8b71e3cfffc2ace7495  cf5f4956a9580bc5e6147816a514232c78c9dc
   41e1c9e661b37d79d8c7a308dd615460cda6fc  df0def7fb8107717ed2274b88f855d18402a72
   53609d2bd5d62d0a1b3e16b71fdb38222d603a  df6c5b6d68b9ac6b8d77c8fbb387c2e321be5d
   56e591f28f96abdbdfe9a272db5ad8f67be133  e126e210d7ca642913bfa6ac457a87e0b7cca8
   68539eec28b5ceaa93c3e0279ee51fba31b14b  e31fc275ff9100c2f52176d8fb78ac1b7af6be
   739e591a62f98df6580d2f23bb25116ef2f8bb  e5f302a2c302b7dbc135534983cd945ed968ec
   77704dfd0f41d99a7cff6b7267a1be1da721c3  ea24ca145464d4a314aa14b6d8533a767aa2e2
   7f5692be9eeef7fce43728c2c35c43c7a0d0b8  f4f3ff16b100e942548a00143ab45e9e1cab40
   84f68b6d16a45574d8361c4722aaf7ef08e022  
   ```
 
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