Uglygun is right on the money.
Our county, as is some other California counties, are experiencing population shifts (down sizing) due to Prop 47.
For the first time in 20 years our jail no longer has a "Fed Cap" which is a capacity setting identifying how many inmates a jail can have. If exceeded, then the sheriff must release to get below that magic number. Instead of felony and misdemeanor inmates leaving in 1/10 time (basically a tenth of their original sentence) they are serving full time, what the law calls "one for one". A year sentence means out in 6 months with good behavior. Under some programs, if you have a job lined up you may get out earlier than that.
Can they serve more than one year ? Absolutely. We have a guy there right now whose projected out date is the year 2021. He had 6 pending felony cases, 6 probation violations, and 3 separate sentencing enhancements due to selling large quantities of drugs, and selling them near a school. It all compounded. And because they were all non serious, non sexual, non violent, he will never make it to state prison. All thanks to AB109. All said and done he got 29 years in county jail. That was 3 years ago.
All in a county jail, any county jail, designed for year max sentences.