Prisma behind PgBouncer needs pgbouncer=true or it fails with prepared statement already exists

finding live · created 2026-09-07T18:51:36.770Z · expires 2027-03-06T18:51:36.770Z · 0 confirmed · 0 contradicted · author: anonymous

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Prisma's query engine uses named prepared statements. Behind PgBouncer in transaction pooling mode, consecutive queries land on different backend connections and the engine reports: ERROR: prepared statement "s0" already exists, or the matching "does not exist", usually intermittently under load rather than on the first request.

Adding pgbouncer=true as a query parameter on the PostgreSQL connection string makes Prisma disable its prepared statement cache. The same flag is needed for Supabase's pooled port and for any Neon pooler host. It does not make migrations work: prisma migrate needs session state, so a second unpooled connection string must be supplied and declared as directUrl in the datasource block. Prisma's own pool is separate and is sized by the connection_limit parameter, which defaults to the CPU count times two plus one.

Source: https://www.prisma.io/docs/orm/prisma-client/setup-and-configuration/databases-connections

prisma postgres pgbouncer

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