The relevant PCI-DSS section says:

3.4 Render PAN unreadable anywhere it is stored (including on portable digital media, backup media, and in logs) by using any of the following approaches:
* One-way hashes based on strong cryptography (hash must be of the entire PAN)
* Truncation (hashing cannot be used to replace the truncated segment of PAN)
* Index tokens and pads (pads must be securely stored)
* Strong cryptography with associated key-management processes and procedures

https://www.pcisecuritystandards.org/documents/pci_dss_v2.pdf

The anywhere it is stored part seems pretty clear - there's no exception for storing PAN data in a RAM based database.

You said your architecture was deemed compliant - If you had a QSA evaluate your environment, this would be a good question to ask him.

The relevant PCI-DSS section says:

3.4 Render PAN unreadable anywhere it is stored (including on portable digital media, backup media, and in logs) by using any of the following approaches:
* One-way hashes based on strong cryptography (hash must be of the entire PAN)
* Truncation (hashing cannot be used to replace the truncated segment of PAN)
* Index tokens and pads (pads must be securely stored)
* Strong cryptography with associated key-management processes and procedures

https://www.pcisecuritystandards.org/documents/pci_dss_v2.pdf

The anywhere it is stored part seems pretty clear - there's no exception for storing unencrypted PAN data in a RAM based database.

You said your architecture was deemed compliant - If you had a QSA evaluate your environment, this would be a good question to ask him.

The relevant PCI-DSS section says:

3.4 Render PAN unreadable anywhere it is stored (including on portable digital media, backup media, and in logs) by using any of the following approaches:
* One-way hashes based on strong cryptography (hash must be of the entire PAN)
* Truncation (hashing cannot be used to replace the truncated segment of PAN)
* Index tokens and pads (pads must be securely stored)
* Strong cryptography with associated key-management processes and procedures

https://www.pcisecuritystandards.org/documents/pci_dss_v2.pdf

The anywhere it is stored part seems pretty clear - there's no exception for storing PAN data in a RAM based database.

The relevant PCI-DSS section says:

3.4 Render PAN unreadable anywhere it is stored (including on portable digital media, backup media, and in logs) by using any of the following approaches:
* One-way hashes based on strong cryptography (hash must be of the entire PAN)
* Truncation (hashing cannot be used to replace the truncated segment of PAN)
* Index tokens and pads (pads must be securely stored)
* Strong cryptography with associated key-management processes and procedures

https://www.pcisecuritystandards.org/documents/pci_dss_v2.pdf

The anywhere it is stored part seems pretty clear - there's no exception for storing PAN data in a RAM based database.

You said your architecture was deemed compliant - If you had a QSA evaluate your environment, this would be a good question to ask him.